Skip to main content

Cpanel does not seem to handle greylisting correctly

Frank Cuypers
Our email domain MAILDOMAIN1 is hosted on cpanel.
Since end of last year, mails from some users on MAILDOMAIN1 to a specific MAILDOMAIN2 are systematically grey listed by MAILDOMAIN2.Sending mails from MAILDOMAIN1 to other domains is no problem.
When sending from MAILDOMAIN1 to MAILDOMAIN2, we get after about an hour a "Undelivered Mail Returned to Sender" message with:
<xxx@MAILDOMAIN2>: host yyy said: 452
    4.1.1 <xxx@MAILDOMAIN2> Greylisting in action, please try again
    later (in reply to RCPT TO command)
and the mail is not delivered.
cpanel shows in the "Track delivery" that the mail was accepted. So my MAILDOMAIN1 hosting provider claims that the error is with MAILDOMAIN2.
If I manually resend the mail after the error message, in most cases it is delivered.But the mail servers should perform the greylisting communication automatically, without manual intervention.
MAILDOMAIN2 claims it is due to the fact that retries send by MAILDOMAIN1 all come from different IP addresses (from enmail.co). So each retry is seen as a new mail which is greylisted again.
 
Is there somtehing in cpanel that needs to be configured to make this work?

Comments

13 comments

Date Votes
  • cPRex Jurassic Moderator

    Hey there!  I'm guessing in this case you don't have any control over MAILDOMAIN2, correct?  Does the manager of the MAILDOMAIN2 system see anything about greylisting in the logs on their end?

    0
  • Frank Cuypers

    Hello,

    Indeed, I have no control over MAILDOMAIN2. 

    As mentioned, the MAILDOMAIN2 manager sees that when greylisting, they see that the resends of MAILDOMAIN1 come each time from a different IP address. Probably due to the fact that enmail.co uses hundreds of dynamically managed IP addresses as a gateway.

    0
  • cPRex Jurassic Moderator

    Unfortunately I don't have a good workaround for this issue as the Greylisting tool only matches IP addresses and not domain names.  If you'd like to see that behavior changed could you submit a feature request over at features.cpanel.net?  If not, I'm happy to submit one for you.

    If all of the IPs are in the same range, the MAILDOMAIN2 admin could whitelist that range in WHM: https://docs.cpanel.net/whm/email/greylisting/#add-an-ip-address-to-the-trusted-hosts-list

    0
  • Frank Cuypers

    The MAILDOMAIN2 admin does not whish to make exceptions...

    0
  • cPRex Jurassic Moderator

    That would be the final answer then - the systems both seem to be working as intended.

    0
  • Frank Cuypers

    Except that for greylisting to work, the resends from MAILDOMAIN1 need to come from the same IP address, which they are not. Every time that a a resend domes form a new IP address, it just restarts a new greylisting session.

    0
  • cPRex Jurassic Moderator

    I'm not sure there is much I can offer for that portion - our documentation states in many areas that we require a static IP address for cPanel functions to work properly, so you may not be able to use that particular email tool with cPanel.

    0
  • Frank Cuypers

    Then why is cpanel using the enmail.co gateways for sending mails? That way cpanel does not use static IP addresses, but dynamic ones.

     

    For clarity; my cpanel based MAILDOMAIN1 sends a mail to MAILDOMAIN2, which starts greylisting. But the resends of my mail to MAILDOMAIN2 have each time a new IP address.

    0
  • cPRex Jurassic Moderator

    We don't - we have no affiliation with enmail.co in any way, so that is likely something that is customized on your machine or from your host.

    0
  • Frank Cuypers

    I am on cpanel 126.0.10. In the e-mail section there is an option "Enmail - Outgoing Email", opening as

    So this is not standard cpanel functionality, but some kind of addon?

    0
  • cPRex Jurassic Moderator

    Correct - this isn't something that is included with cPanel by default, so that has to have been added by your host.

    0
  • Frank Cuypers

    https://brixly.uk/knowledgebase/email-hosting/enmail-gateway-managing-outgoing-emails-in-cpanel 

    0
  • Frank Cuypers

    Thanks for the clarification

    0

Please sign in to leave a comment.

Didn't find what you were looking for?

New post