If emails leaving your server are not delivering well (either because they're filtered as spam or bounce back), your server may be affected by a poor email reputation score.
Here are some measures that can be taken:
1- Your server might be actively sending spam; check your logs!
It's important to ensure that your server is not actively sending spam before taking any further steps. While such a verification can be quite complex, here are some tips:
- For cPanel servers, in WHM check your View Sent Summary to see which account is sending the most emails and to spot a high number of failed or deferred sends.
If you have SSH access (advanced users only!), consult the email log for detailed information on who is sending, and when: /var/log/exim_mainlog - For Plesk servers, you'll find the logs here: /usr/local/psa/var/log/maillog
In most cases, there is an infected malware script sending massive amounts of emails. If you find one such script, your account has been hacked and an immediate SiteSafe cleanup is highly recommended.
If you are unable to find the spamming script, please contact support.
2- Check your Reverse DNS (also called PTR) Record
A Reverse DNS (also called RDNS or PTR record) maps an IP address to a hostname. Check your server's Reverse DNS here: http://mxtoolbox.com/ReverseLookup.aspx
If the RDNS does not point to your server's primary hostname, please contact support requesting that this be corrected.
3- Your server's mail IP may be blacklisted
If your IP has been used to send out spam, it may be listed on a blacklist. Check your IP against known blacklists here: http://mxtoolbox.com/blacklists.aspx
If listed and you are sure your server is not actively sending spam, you may request a delist by following the on-page instructions for the blacklist in question, or contact our suport team requesting assistance.
4- Your server's mail IP may have poor reputation
Several vendors now track IP reputation, in addition to blacklists. The following are the most important:
- SenderBase: http://www.senderbase.org/static/email/
Search your IP using their search tool. If reputation is poor, you may request a manual reputation reset by contacting support@senderbase.org - McAfee: http://www.mcafee.com/us/threat-center.aspx
Search for your server's IP address and if reputation is RED, email ts-feedback@mcafee.com requesting a reputation reset. - TrendMicro: https://ers.trendmicro.com/reputations/index
Search by IP and request a delist directly via their online form if you have poor reputation - Symantec: http://ipremoval.sms.symantec.com/lookup/
After the search with CAPTCHA, fill out their delist form if you have negative reputation
These providers use Microsoft's proprietary system, and so you'll need to request a reputation delist via this form: https://support.live.com/eform.aspx?productKey=edfsmsbl3&ct=eformts
6- Nothing works? Try changing the sending IP
In certain extreme circumstances, it may be useful to change the sending IP of your server. This is only possible if you have multiple IPs bound to your server.
With CPanel, here is a procedure to do this: https://documentation.cpanel.net/display/CKB/How+to+Configure+Exim%27s+Outgoing+IP+Address
Careful: don't change sending IPs unless you are sure that you are not sending SPAM out anymore, otherwise these new IPs might also quickly suffer from poor reputation.
