I was reading through Campaign Monitor's guide to preheaders recently.
Admittedly I hadn't really thought about them until I learned of their importance and the impact they have on how an email will look with and without them in the inbox.
A couple of comments in the blog post mention if the hidden span preheader technique influences spam filters. Well with SpamAssassin the span preheader triggered the "REMOVE_BEFORE_LINK" rule on a recent test I did with an email campaign (Not within Campaign Monitor).
The template code for the related area (excluding usual boilerplate layout before and after):
<span class="preheader" style="display:none !important; font-size:1px; color:#ffffff;">Preheader text here</span> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr> <td align="center" valign="top"> <table border="0" cellpadding="0" cellspacing="0" width="600" style="width:600px;"> <tr> <td align="center" valign="top"> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr> <td align="center" valign="top" style="padding-top:10px;padding-bottom:10px;">Email not displaying correctly? <a href="#">Click here</a> to view this email in your web browser</td> </tr> </table> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr> <!-- The rest of template after web version link --> <td align="left" valign="top"></td> </tr> </table> </td> </tr> </table> </td> </tr> </table>
I just used general text content in this example, but meaningful text was used in the test email send which I ran the report on.
My first thought was maybe the font-size of 1px was an issue, but its not. It literally the presence of a span in the position its in.
Removal of the preheader span and the mentioned SpamAssassin rule isn't triggered. I could rework the position of my web version text, but has anyone come across this before?
In total my email scored 2.2 which is not classed as spam (anything 3 or higher is a concern) but obviously 2.0 points for one rule is concerning.
I agree this is a concern. The spam rule would only be triggered if certain phrases are used in the preheader text though, wouldn't it?
What phrase did you use that might have triggered the rule? I don't suppose Apache publish a list of 'bad' phrases.
Specific preheader text was:
"Do you keep meaning to apply to college but can't find the time?"
Perhaps a bit long, the only area I could see it being a problem would be the word apply, but other than that, I'd deem it OK.
What might have caused the spam score is the "color:#ffffff;". White text on white bg used to be a spam concern a few years ago, so it might be that.