SOLVED SMTP connection from - lost while reading message data

[Rafael Gomes]

Hello,

I use a VPS Server with centOS 7 and Cpanel 74.0 (Build 10). One of my customers are trying to send me some emails but I'm unable to receive them:

[root@vps ~]# grep /var/log/exim_mainlog | tail
2018-11-16 09:59:12.171 [13336] SMTP connection from mail. (Hostname) [IPServer]:34366 I=[IPServer]:25 lost while reading message data (header)

There's no filter on my VPS. It's a problem that happens sporadically.

Could you guys, please, help me with this one?

 

[cPanelMichael]

Hello @Rafael Gomes,

This normally happens when there's a firewall or network connection issue between your server and the workstation making the connection attempt. Are you using any firewall rule management utilities such as CSF? If so, check to make sure the customer's IP address isn't blocked. Also, can you verify if you are using any third-party email plugins such as MailScanner?

Thank you.

 

[Rafael Gomes]

Hello,

This situation was explained today, seems to be a problem with MTU from the user who attempts to send us some emails. Maximum size segment (From the client) was adjusted to send out a smaller header.

Thanks

 

[cPanelMichael]

Hello @Rafael Gomes,

I'm glad to see you were able to identify the source of the issue. Thanks for taking the time to share the outcome!