Are Blocklisted Link Shorteners Getting Your Emails Blocked?

Have you ever used a link shortener on any of your email marketing campaigns?

They’re a handy way to send a long URL to someone using just a few characters. And while they’re nothing new (TinyURL turns 10 in January 2012), they’ve become particularly popular since the rise of Twitter, Facebook and other communication mediums where space is at a premium.


Chances are, you’ve looked at a long link in one of your emails and thought, “It’d be nice if that link weren’t quite so long,” and been tempted to use a link shortening service.

But did you know that link shorteners could potentially hurt your email deliverability rates?

How Link Shorteners Can Affect Deliverability

Link shorteners are handy for trimming down long URLs.

But in addition to offering that convenience, they perform one other function: they mask where a link actually goes.

This makes them appealing to spammers who either:

  • Don’t want recipients to see their actual website domains, or
  • Don’t want ISPs and other organizations to be able to filter out their spam by blocking emails that have the spammer’s domain in the body of the email.

Of course, some legitimate email marketers may find the idea of shortening links appealing, too. This is particularly true for those who send plain text emails, since in an HTML email you can simply link whatever text or image you want, as you would on a web page.

The potential problem happens when both a spammer and you use the same link shortener in your emails. If one or more ISPs start blocking emails that include that link shortening domain (to block the spammer), they may inadvertently block your emails, too.

So Which Link Shorteners Are Blocklisted?

I wanted to find out how much of a problem this could really be – after all, everything I’ve said above is true in theory, but I didn’t know how much (or if) it was actually happening – so I cracked open my browser, a spreadsheet and got to researching.

I checked 24 popular link shorteners against three popular URI blocklists:

These lists are used by some ISPs to determine whether an email should be placed in the inbox, bulk folder or neither. If the body of your email includes a link to a blocklisted domain, an ISP may choose to not deliver it to subscribers’ inboxes.

Before you look at the results below, keep in mind these results can change at any time. This data is as of June 23rd, 2011. A blocklisted domain could be delisted now, or tomorrow, and an unlisted domain could get listed at any time.

OK, with that said, here’s what I found. Results are ordered by Alexa Rank, starting with the most popular, bit.ly:

Link ShortenerAlexa RankListed in DBL?Listed in SURBL?Listed in URIBL?
bit.ly152YesNoNo
tinyurl.com747NoNoNo
goo.gl855NoNoWhitelisted 1
ow.ly1966YesNoNo
t.co2403NoNoNo
su.pr6539YesNoNo
budurl.com6907NoNoNo
is.gd8149NoNoWhitelisted 1
lnk.co10,250YesNoYes
fb.me11,564NoNoNo
cli.gs41,012YesNoYes
deck.ly72,661NoNoNo
snipurl.com73,378NoNoNo
tr.im202,662NoNoNo
fur.ly249,983NoNoYes
twurl.nl307,728NoNoYes
u.nu585,984NoNoNo
short.ie695,684YesNoNo
blinky.me1,108,121NoNoNo
kl.am1,206,876NoNoNo
zi.ma1,997,505NoNoNo
poprl.com4,471,928NoNoNo
hex.io5,784,912NoNoNo
ad.vuN/ANoNoNo


Yes, I know Alexa rank isn’t a perfect measure of popularity, but Alexa had traffic stats on more of these link-shortening domains than Compete, Quantcast or anyone else I tried.

What Do These Listings Mean?

As you can see, none of the popular link shorteners were listed on SURBL as of June 23, 2011. A couple, goo.gl and is.gd, were actually whitelisted by URIBL.

However, eight of the link shorteners were listed in URIBL or the Spamhaus DBL. So if you sent out an email that included a link to one of those domains, your email delivery rate could have been affected.

Now, the point here is not “OK, so just avoid those ones that were listed.” To re-emphasize from before, these results don’t mean unlisted link shorteners will never cause problems. Any of them, even the ones currently whitelisted, could potentially be blocklisted in the future.

Here’s what you should take away from these findings:

  • Link shorteners are handy for trimming long URLs in tweets, Facebook statuses, and similar venues where space is at a premium. But space isn’t at the same premium in an email as it is on social media.
  • Whatever convenience link shorteners offer in an email is outweighed by the potential for those shortened links to hurt your email deliverability.
  • If you’re currently using these or other potentially abused link shorteners in your email marketing campaigns, stop!

Don’t Like Long Links In Your Emails? Here Are Some Options.

  • Set up your own link shortener. If you’re sufficiently tech-savvy, you can install a link-shortening script on a domain of your own. (You’ll need to come up with a short, available domain and register it.)Here are a few different options if you’re interested in this: YOURLS, Phurl.
  • Send emails with an HTML version instead of plain text-only emails. If you’re sending HTML email, all you need to do to not have long URLs appear in your emails is to link up appropriate text or images instead of just putting the full URL on display for subscribers.

One last note on links and emails: if you’re sending subscribers a link to a page on your website, isn’t it best for them to be able to see that’s where the link goes? If you see a shortened link in an email, don’t you pause and wonder where it’s going to take you? I sure do.

That’s why with AWeber’ email analytics you can track clicks using your own domain.

Sure, not all links in your emails go to your own website, but a lot of them do. Showing subscribers that they’re going to end up on your site may be the difference between someone clicking and not clicking.

Have You Used Link Shorteners In Your Email Marketing Campaigns?

If so, what was the reason? (I’m not being sarcastic; I really want to know, because I’m not seeing a reason. Enlighten me. 🙂 ) Have you seen any impact on clicks or email deliverability as a result of using them?

UPDATE: Steve at Word to the Wise has more on bit.ly blocking issues.


1. URIBL’s whitelist “contains legit domain names that [they] do not want to show up on any other URIBL lists.” More on their lists here.

65 Comments

  1. kathrine bocsh

    6/28/2011 6:40 pm

    this post is interesting yet helpful , thanks for it

  2. Mark Brownlow

    6/29/2011 1:04 am

    Great research Justin – thanks for sharing with us!

  3. Marla Tabaka

    6/30/2011 10:57 am

    Great information Justin. Thanks for putting the research behind this!

  4. Peter Gold

    6/30/2011 11:05 am

    Justin

    Great post and thanks for raising this. I have been “testing” various different options and did wonder the same. I have found within a lot of corporate environments these redirect links just don’t work! As I use plain text a lot of the time trying to use a tracking link is difficult so have in some cases reverted to using a full URL albeit within my own site as it has its own URL shortening tool which works great. This way, I can create unique links direct to my site that are 301’d to the “actual” page and does not get blocked by any corporate systems.

    Hope that all makes sense.

  5. Adele Berenstein

    6/30/2011 11:11 am

    Doesn’t Aweber substitute its own link even when we put in our own shortened link?

    Why wouldn’t Aweber warn us against using the link shorteners with a bad reputation. You warn us about links that no longer work or that take too long to respond. Maybe you should warn us about possible link shortner bans.

    just an idea.

    Thanks for the article. I will change my link shortener provider. I do create a text version of my emails in case people don’t take the full newsletter version.

  6. Sidz

    6/30/2011 12:40 pm

    Excellent post. Thanks for sharing this valuable information. I’ve used a lot of bitly and will probably go by what the post says in all my email campaigns from here on!. 😉 Cheers.

  7. Chris

    6/30/2011 1:04 pm

    What if you are using Aweber click tracking that THEN redirects to a url shortener?

    For HMTL emails, the url shortened url would then appear as text only. Is that still banned too or is it just if it appears within the HTML code too?

    Seems pretty dumb to me that one database would blacklist some but not others. They are used by thousands each, so you can’t label all users of them.

  8. Paul Keetch

    6/30/2011 1:08 pm

    Very good article on the potential perils of using a public link shortening tool in place of your longer links.

    In addition to potentially having your email blocked by the ISP or a user’s app-based spam filter, I have had the experience of list members emailing me to tell me that they absolutely, positively will not click a cloaked link for the simple reason that they don’t know where it will send them.

    Twitter has built in a tool for users to see the destination of cloaked/shortened links for just this reason.

    If you run a wordpress site there’s an easy (and free) solution to customizing your own shortened links. It’s a tool called “pretty link” and the lite version of the plugin is available at no charge.

    You can use www.yourdomain.com/x72 auto-generated short links OR you can customize the trailing text to be anything you want (as in www.yourdomain.com/mylink).

    I’ve been using pretty link for some time now and it has been a good tool for me. The lite version even tracks clicks/hits on the link.

    Thanks again for bringing this up!

  9. Greg Lins

    6/30/2011 1:49 pm

    Justin,

    This is all good information, but did you know that AWeber’s forms restrict the length of a URL such that one is forced to use a link shortener?

    That’s right. I had a campaign recently where we were pointing to sub-sub-pages, and on top of that they were password protected. We used a password token so users wouldn’t need to know the password, which adds about 20-25 characters to the end of the URL. Add all that up, it’s a long URL, but not outrageous either. Just normal use stuff….

    Please help us by increasing URL field sizes!

  10. Sean Breslin

    6/30/2011 3:12 pm

    This was informative… I am trying to ween myself off bit.ly so it was a timely piece! The point about html and links from images was a good one.

  11. Paul Keetch

    6/30/2011 3:14 pm

    @Justin – you’re right about that, for sure. Another “long url” creator is the UTM links used to track source, campaign, etc.

    I like the idea of a branded shortener (instead of a generic one) because it still has credibility and is more likely to be clicked (and not blocked).

    Lengthening the URL capability is probably not the solution since long URLs tend to get broken in many online email readers, including hotmail & yahoo.

    Add to that the increasing use of mobile phones to check email and long links are just a bad idea all around.

  12. Kate

    6/30/2011 3:18 pm

    I have to admit, I rarely click on shortened links because in truth, I don’t like traveling to unknown destinations.

    But my 1st website has a crazy long domain. So URLs to the 500+ pages are ridiculous. My 2nd website got a bit shorter and my 3rd domain is reasonable. I figure by my 10th website, I’ll get domain naming under control. 🙂

    Anyway, that’s why I like using bit.ly. But alas, it is currently on the X list. Sigh… Back to ugly URLs in my newsletter.

    But better ugly than spammy.

  13. Justin Premick

    6/30/2011 3:19 pm

    Thanks all for your replies and feedback!

    Peter,

    I follow what you’re saying. 🙂 You might consider trying including an HTML version of your emails, though… that way you could simply link up whatever text you wanted and not worry about the length of the URL itself.

    Adele,

    You’re right to say that AWeber does offer click tracking, and that this can change what domain a link in your emails points to. However, you can avoid this either by using our Email Analytics tools to track clicks using your own domain, or disabling click tracking.

    With respect to adding shortened domains to the Link Checker – that’s an interesting idea. Thanks!

    Chris,

    URL blacklists, as far as I know, are only checking what’s actually in the email. (After all, if ISPs followed the links in emails and then checked those links against URI blacklists, there’d be no reason for a spammer to use a link shortener.)

    Paul,

    Thanks for sharing that plugin – using one’s own domain for links is the ideal thing to do, and it sounds like that plugin could potentially be helpful.

    Greg,

    Sorry, but I don’t know what form you’re referring to. Based on what you’re saying, it doesn’t sound like you’re referring to our signup forms (which is what I tend to think of when I see “AWeber’s forms”), and I’m not sure where you’d be entering that information. I’ll email you to get some more details.

  14. Meg Collins

    6/30/2011 3:45 pm

    I use the Amazon.com link shortener because (not to be a smartass), but when the links to Amazon are NOT shortened, they all show up as being broken by Aweber (when they in fact aren’t). I think it’s just that they are too long.

    Also, I use it because in plaintext, I don’t want a URL that is 100 characters long all over my emails.
    Word?

  15. Etienne Juneau

    6/30/2011 3:57 pm

    Hi Justin,

    I’ve been using TinyURL for some time and haven’t noticed any drop in response.

    Based on your research, that fits.

    Thanks,

    Etienne

  16. Dale

    6/30/2011 4:02 pm

    What about www.tiny.cc I’m been using it for some time.

  17. Angela

    6/30/2011 10:33 pm

    I’ve been using tiny url for quite some time. After reading different articles about it. I recently decided to use bit.ly to shorten my url’s. Now I’m reading articles about bit.ly being listed in DBL. :-<

    Thanks for your interesting information.

  18. Eruwan Gerry

    7/1/2011 1:36 am

    Thanks for the great sharing Justin! Wouldn’t have known this if you guys didn’t share it here. Thanks again.

  19. gonzalo

    7/1/2011 11:33 am

    Hi very good information and I did not use bit.ly had trouble in the response. Thank you very much for the info

  20. Kate

    7/1/2011 12:07 pm

    Justin,

    Thank you for your email on blacklists of link shorteners. I ended up using my own link shortener which brands my site vs using bit.ly links or the unpredictable long form.

    I never would have made the leap if you hadn’t pointed this out. AWeber emails are worth their weight in gold.

    Super thanks! Kate

  21. Laurie Lacey

    7/5/2011 7:02 am

    I use goo.gl, which is Google Chrome’s own shorterner, included in the Chrome Browser. I don’t think anyone will blacklist the Google Chrome shorterner for some time, and I notice this is confirmed in your research. It’s so simple to browse and shorten URL’s, directly from the URL page. It’s beautiful! I do it because long URL’s in a text newsletter are unsightly, and many people will hesitate to click long URLS that are full of numbers and weird code. So, I’d rather have them shortened.

    Yes, I could move to html newsletters, but they have deliverability problems that text newsletters do not have.

  22. Mike Chiasson

    7/7/2011 10:53 am

    Awesome post! Thanks for sharing! I run a barracuda spam filter and its unbelievable how sensitive these things can be when something is blacklisted.

  23. Robert T

    7/7/2011 11:23 am

    Excellent research and great info for any IM. Thank you, sir.

  24. Gwenn

    7/7/2011 11:54 am

    Thank you! I am just writing my first series of autoresponders and learning slowly, step by step.

    Some of my links look long but I will now just leave them quite happily!

    Much appreciated.

  25. Dr. Michael Haley

    7/7/2011 12:43 pm

    I have been using “Pretty Link” for my wordpress blog and made a screen capture video to demonstrate how it works at http://www.seowebmeeting.com/pretty-link/ . It has been quite beneficial for me as a link shortener for those links I will use over and over again. As an example, I used the shortened URL http://drhaley.com/bo-email (which isn’t that short) to send people to my aweber hosted email sign up page for a certain at home business called “Beyond Organic” (the “bo” part). Having a “descriptive” short URL helps me to remember it for future use. Of course I can always “log in” and check stats on all of my short URL’s which is nice.

  26. Borge Hansen

    7/7/2011 1:43 pm

    I have been around since the Stone Age, and the reason for these shortened links was that you would be more likely to click on a short and precise link than some long and incomprehensible link. There is a point there.

    But I don’t see the point in that a link like: http://6pn.com/StingerVideos should be more likely to be considered spam than: http://www.stingervideos.com/hop/nikihunden

    You could just as well hide some spam in the last. Not a problem.

    But It’s good to have this kind of info what is considered spam. So keep up the good work!

  27. John Panico

    7/7/2011 3:23 pm

    Justin…some handy stuff there. Let me ask you a couple of quick questions from a novice…
    Is there a URL shortener that AWEBER recommends at this time?
    If you are using HTML, then it may not matter (did I understand you correctly?
    Does AWEBER advocate text vs html emails?

    Thanks!

  28. Justin Premick

    7/7/2011 3:40 pm

    Borge,

    It’s a question of who else is linking to a domain in their emails.

    If you’re the only one using a shortened domain, then it’s perfectly fine, but that’s not what happens in the case of shared, public link shorteners like the ones mentioned here.

    John,

    We don’t recommend the use of *any* public URL shortener, for the reasons outlined in this post.

    The difference isn’t really a question of text vs. HTML – it matters either way. You don’t want to link in your emails to a domain that spammers may have abused.

    What you want to do is link to your site directly (after all, that’s the one where subscribers signed up and the one that appears – or should appear – in the “from” line of your emails).

    We don’t specifically advocate plain text over HTML. That’s really a personal choice that takes into consideration a number of factors. For what it’s worth, I personally favor using HTML.

  29. Borge Hansen

    7/7/2011 3:51 pm

    Justin

    Then it is wrong to blacklist links just because they are short! Period

    With all respect

  30. Michele Price

    7/7/2011 4:07 pm

    What I am not seeing addressed which is why I use shortner links is to track the activity. If I have a link in one email and that same link on twitter then that same link on facebook, I want to know which is driving more traffic , hence shortner.

    It has nothing to do with hiding url.

  31. John

    7/7/2011 4:11 pm

    Wow, great advice, it hadn’t occured to me before this might be an issue.

  32. Gary McLaren

    7/7/2011 11:00 pm

    Great post. This is something I have occasionally noticed when using shorteners, particularly some time ago when I was using TinyUrl more. More recently I’ve been using Bit.ly so this article was an eyeopener there. Another popular shortener used in many WordPress blogs is wp.me.

  33. Justin Premick

    7/8/2011 10:47 am

    Michele,

    If you use Google Analytics (and I would imagine something similar exists in most other web analytics software), you can make those links unique by adding the utm_source parameter (or one of the others) to the end of each link.

    For example, if I were linking to the AWeber homepage from Facebook, Twitter and one of my follow up messages, I might use the following three links:

    https://www.aweber.com/?utm_source=facebook
    https://www.aweber.com/?utm_source=twitter
    https://www.aweber.com/?utm_source=aweber

    You might find this Google Analytics URL builder helpful:

    http://www.google.com/support/analytics/bin/answer.py?answer=55578

  34. Rex Harris

    7/8/2011 3:22 pm

    I heard about this happening a few days ago. There have been several top marketers who have been feeling the effects of this recently, including me. You note here that TinyURL is not listed in DBL but I know first hand that some systems are blocking it as well. Thanks for sharing this! Time to start masking tracking links with sub domains I guess 😉 !!

    Cheers!

  35. Will Kenny

    7/11/2011 5:46 pm

    Alerting us to the dangers seems sound, but just saying “Don’t do it” does not seem helpful, especially with regard to text emails. The problem of those URLs breaking over lines, even for fairly short ones, is real, and a solution besides abstinence would be helpful.

    Now, Justin writes, “We don’t specifically advocate plain text over HTML. That’s really a personal choice that takes into consideration a number of factors. For what it’s worth, I personally favor using HTML.” It is true, you may not recommend using text rather than e-mail.

    But your own knowledge base says, “When creating message to send to your list, you should always include a plain-text version, even if you do also include HTML,” and some people prefer to receive text versions because they trust them more. As your knowledge base points out, “HTML-only messages are more likely to be content filtered.” It also says, “That doesn’t mean you can scrap your text message. Neither ISPs nor subscribers will be happy with you if you do.”

    Warnings are nice, help is better.

  36. Justin Premick

    7/12/2011 1:13 pm

    Hi Will,

    Thanks for the feedback!

    To your point that we recommend including a plain text message when sending HTML, you’re right – that is something we suggest, primarily because while most email clients support HTML, in some cases the user may choose to disable HTML. That’s a fairly rare occurrence, but it’s still worthwhile to include a plain text version.

    To clarify, what I mean by my suggestion in this article to “send HTML email instead of plain text” is that you should send an email that includes an HTML version (which will be seen by a significant majority of your subscribers) and also a plain text version (which will be seen by those who have disabled HTML in their email programs or whose email programs do not support HTML). Sorry for any confusion there.

    You’re right, in some cases a long plain text URL may be split onto 2 lines by some recipients’ email clients, and that has the potential to break the link. I would argue that by including an HTML version of your emails, you greatly reduce (if not quite eliminate) this risk by greatly reducing the number of people who will so much as see your plain text version.

    That said, if you refuse to include an HTML version of your emails, you do have the opportunity to include a shortened link that is on a domain you yourself own, rather than any of the publicly shared ones listed in this post. A few such options are listed near the end of the post, and a few people were kind enough to suggest others in the comments.

  37. Jennifer Leake

    7/12/2011 11:18 pm

    Thanks for the heads-up Justin. I am using a shortened link for TeleClasses and some give-aways. These shortened links are in my Auto-responder tips. When I change something, I go to my budurl account and change the webpage. The link is still the same in all the autoresponders – but they are directed to a different page when it is clicked on.

    Otherwise, I would have to revisit each autoresponder and make the change. Am I missing a simpler way to do it in AWeber? Ideas anyone?

  38. Borge Hansen

    7/13/2011 2:35 am

    Hi everyone

    This has been an interesting thread to follow so far. Justin whether or not we agree on the subject of short links, it’s a fact that they are being considered as possible spam by some programs. My point here is that you can do that with all links.

    But Justin you have provided us with great information. Since why use links in our emails that spam checkers might reject? Is this checked in the spam checker that Aweber use in our follow up emails?

    Thanks Justin and all commentators

  39. Justin Premick

    7/13/2011 12:26 pm

    Jennifer,

    If the link in question appears in multiple messages, and changes from time to time, you could use a Global Text Snippet to save time. Details here: https://www.aweber.com/faq/questions/562/How+Do+I+Use+Global+Text+Snippets%3F

    Borge,

    That’s not included in the Link Checker at this time, but that’s an interesting idea – thanks!

  40. Are link shorteners costing you sales?

    7/14/2011 4:06 pm

    […] Read the article here […]

  41. Rod Beckwith

    7/20/2011 3:15 pm

    Excellent article Justin and I know that this can absolutely happen as I ran a URL shortening service that had an issue like this. The best advice is to get your own script with a short URL.

  42. Mike G.

    7/20/2011 4:35 pm

    That’s enlightening because I have been using bit.ly in some cases. What I normally do for affiliate programs I’m promoting on an ongoing basis is I’ve set up a ‘recommends’ folder for my domain and then in that set up a folder for each program with an index file in it that redirects to the site. So my link looks like: www.mydomain.com/recommends/joesproduct

  43. Michael

    7/20/2011 3:36 pm

    I have read warnings several times that affiliate commissions can be redirected to pay someone else if a url showing the affiliate ID is used without cloaking. How else can we protect our payments from being stolen?

  44. Marius

    7/20/2011 3:55 pm

    Excellent article.
    Thanks for taking the time to share a valuable piece of information.
    I never even thought url shorteners were blacklisted.
    Thanks! (And keep up the great service too)

  45. Dylan

    7/20/2011 7:51 pm

    There are free ways of tracking links inside of your WordPress admin.

    If you use wordpress I can share a little simple bit of software that you can use. Click on my name and I’ll share.

    Thanks for posting this. I just can’t justify using those URL shorten services. I think long term you should use something you get lots of control over. Imagine having a nice link somewhere that is bringing you cash and all of a sudden, it’s gone.

    I suggest wordpress not just for blogs. You can make your wordpress site look like website with nothing to hint of blog.

    Anyway anyone here that wants a solution that is super user friendly and controllable from your wordpress admin area, get in touch with me.

    Thanks,
    Dylan

  46. frank

    7/21/2011 12:20 am

    This is helpful. It has broadened my knowledge.

  47. Bettie Wylie

    7/21/2011 12:43 am

    Hi Justin,

    It’s me… the lousy list builder. 🙂
    I do use plain text mostly in my email, but html with some anchor textas well. I currently have the Affiliate Link (WordPress) Plugin installed, but I

  48. JayJay

    7/21/2011 7:24 am

    One thing always bothers me. When you are entering a comment on a blog and use a shortened URL, does Google recognize that as a back link, or do they prefer the full URL address? I have never been able to find the answer to this questions – any ideas?

    Thanks for the very interesting article..

  49. Justin Premick

    7/21/2011 2:44 pm

    Bettie,

    It sounds like you’re referring to tracking visits to those links overall (including visits not related to your email campaigns). In that case, I would check to see whether that plugin offers any sort of built-in tracking capabilities. Depending on how that plugin works, you could also potentially use web analytics software such as Google Analytics to measure visits to each of those links.

    JayJay,

    I’m not sure, to be honest… based on my limited knowledge of SEO, the full URL would be better, but that’s really a question for all the SEO whiz kids out there. 🙂

  50. Ben Fitts

    7/28/2011 5:46 pm

    Funny thing is YOUR link tracker ALSO causes triggers in spam filters.

    A buddy of mine just reported one of my aweber emails going into a spam filter. It was showing a spam score of 0 and 0 complaints.

    The only thing I could figure was that I was using your link shortener.

    I sent a second email the next day without the aweber link shortener and…. it went through just fine. My buddy reported the emails came directly to his inbox not his spam folder.