Emails from a specific email address are getting delayed and delivered all at once randomly
Problem reported by Sam - 11/26/2019 at 4:32 PM
Our Smartermail instance is hosted in our office, but we also have a mail server in our production environment that sends out emails as some of the email accounts that exist in Smartermail. For this example, I will use support@testcompany.com. This account exists in our smartermail instance but when users perform a password reset in our application, our application sends out a password reset mail through our production mail server with the same account. Support@testcompany.com is also used to send out various other system alerts from production as well.

It seems that since I updated smartermail from 15.x to 7242, employees have not been consistently receiving emails from support@testcompany.com. Often times employees don't receive emails from that address at all. Other times, they receive dozens of emails from that address all at once usually hours after they are expected to come.

In Smartermail, I have done everything I've can to ensure that support@testcompany.com and the mail server it is coming from is whitelisted:
-IP of the mail server is in the SMTP whitelist
-The IP is in the IP bypass list with spam filtering and greylisting disabled
-testcompany.com is in the trusted domains list
-support@testcompany.com is in the trusted email address list
-support@testcompany.com is not in an internal blocked senders list
-the mail server is not IDS blocked
-greylisting is disabled
-I can see traffic from the production mail server being allowed on our office firewall
-the emails that do come through show that the email is a trusted sender and spam filtering was skipped on them

I am not really seeing anything in the SMTP logs indicating emails from support@testcompany.com or the production mail server are being blocked. Is there anywhere else that I may have missed?

2 Replies

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Sébastien Riccio Replied
Hello, Is your "outside" production mail server only send mail for your domain or also receives mail for the domains ?
Are the mails that you don't receive on smartermail adressed to the same domain as the sender? 

Your description looks a bit like a split-domain configuration where you have different mail servers handling mails for the same domain.

Maybe you should check the smtp out log on the sending server to check if it actually tries to send it to the correct place.

Sébastien Riccio System & Network Admin https://swisscenter.com
Sam Replied
My outside production mail server is only able to send out mail for the domain. It does not receive mail.

All of the outbound mail sent out returns to our local smartermail server.

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