Spam filtering: No, Gmail doesn’t like links

A rather big part of my weekly newsletter goes out to Gmail accounts. Too bad, if those emails don’t make it through the spam filter to the inbox. But hey, I got my lesson learned… ;-)

My bad

Call me a stupido now – everyone knows that including links in newsletters, which have been cut using popular link shorteners like or, isn’t a good idea. Those domains, which seem generally trustworthy to many of us, are just too often abused by spammers. Thus, they are frequently listed on blacklists and most likely a strong spam signal within spam filtering models.

Well, I was certainly aware of that. Nevertheless, the newsletter had to be deployed in a hurry. (Guess you know that. ;-) ) By just placing the text in my regular greeting paragraph, instead of hyperlinking, I thought everything should be fine. The hyperlink was spared in order to prevent a false phishing alarm in Thunderbird and other clients. Such an alarm is often caused by having a link text (e.g. “”) over a completely different URL (e.g. “”) that has perhaps been inserted by the email service provider before the send-out.

Does “” mean “spam” to Gmail?

Anyway, I was wrong. As you might know, Gmail and others get very motivated when it comes to detecting possible links in emails, which haven’t been hyperlinked deliberately by the sender. Possible phone numbers are automatically converted to clickable “tel:” links (I wrote about it on a while ago). The same goes for possible hyperlinks like the characters “”. So Gmail hyperlinked my text, then it sent the email to the spam filter. And it seems that the link alone was enough to trigger an alarm in my main Gmail inbox:

The left screenshot shows the email containing the, which Gmail considers to be spam, the right screenshot shows the “clean” one without any mention:

Gmail filteres because of a link No link, then the email passes

(All sending IPs I tested got a Return Path Sender Score of 95 or more. That’s very reputable. In case you are wondering about – the result is the same for

Lessons learned:

  1. Although other filtering rules can override it, don’t do links (and other shortening services), because they might cause spam false positives and get some of your emails filtered unnecessarily.
  2. If you still want to use them: Placing the link as HTML text only without any anchor tags around it and, in addition, breaking the link structure by inserting a <span> tag (e.g. bit.<span>ly/KDD7Md</span>) prevents Gmail from hyperlinking the text. This way, the email passes the filter. (Don’t forget to adapt the link in your text part, too.)
  3. Interesting that even with personal sorting rules set, the priority flag gets killed when the email seems to be spam to Gmail (compare the priority symbol in both screenshots).
  4. The same email might bet filtered before going to inbox A, but pass without any problems to inbox B. I.e., including a link doesn’t necessarily mean that your email gets junked. (I wouldn’t be too surprised if not even the Google Engineers were able to explain the outcomes of the rule set: Gmail is a “black box”.)
  5. Overall, take your time and do a rendering and spam filter test – especially if you try something awkwardly new.


As a side note:

Lesson is learned. Nevertheless, you will probably see other newsletters from my part containing shortened links, some of which even point to a different URL than what the link text says. That is simply because it’s how I currently store the bookmarks in my database. The whole newsletter is assembled with a mouse click based on those database entries, with the only exception of the editorial. Until I get infected with a bit of handicrafts fever again, it would be nice if you just add to you Google Contacts, circle me perhaps and move the emails to the inbox in case of a false positive. And oh, feel free to comment on my weekly recaps – I’m always interested in feedback (what did you find interesting on the web, did I miss something, etc.). Thank’s in advance. :-)

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2 Responses to Spam filtering: No, Gmail doesn’t like links

  1. Interesting. RT @absolit Spam filtering: No, Gmail doesn’t like links:

  2. but with this methode the link becomes just a text how can we let the link clickable without going spam ???

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