x-mailer header, phpmailer and spam filters

问题:

I am a newsletter plugin developer for WordPress (Knews). It uses phpmailer to send.

One user has contacted with me about an issue: all his emails (sent through phpmailer) goes to spam.

He has solved adding a header param:

$mail->XMailer...

Phpmailer uses a default x-mailer param (phpmailer) if you doesn't set it, is this value bad for spam filters? What was the better value?

Thanks, Carles Reverter.

回答1:

Setting an X-Mailer to "gibberish" can increase the bad score of Spam engines, not setting it shouldn't make any difference.

Anyway in reality it is really hard to answer this kind of questions because it varies a lot.

To answer your question I referred to this document which cites scores based on a list of rules: http://webmail.uni-weimar.de/antispam/criteria.html

As you can see there's a line citing:

'X-Mailer' line contains gibberish X_MAILER_GIBBERISH 0.001