When my clients use OUTLOOK to send emails they sometimes got the "Message has lines too long for transport" error. I send a ticket to CPANEL and they told me this:
So I need to know where to change this. A lot of clients are having problem with this.Looking at your server, you have Magicspam setup on your server. This service is not controlled by cPanel but does create custom transports, which is where the problem resides.
[19:44:19 azathoth root@94525197 ~]cPs# grep -i "Message has lines too long for transport" /var/log/exim_mainlog | head -n2
2023-01-23 08:55:38 1pJxIP-000DjV-7t ** email@example.com R=remoteserver_route T=mailchannels_smtp: message has lines too long for transport
2023-01-24 16:58:33 1pKRJJ-0007US-Td ** firstname.lastname@example.org R=remoteserver_route T=mailchannels_smtp: message has lines too long for transport
I see no message length has been added to these transports. Please look at the following article with your system administrator and include that in your custom transports.
"Message has lines too long for transport" with custom routers in v102+ : https://support.cpanel.net/hc/en-us/art ... s-in-v102-
I am confident the knowledge shared in the above article will guide you towards solving the issue you have outlined in this request. Would you please review the article and let me know if you have any outstanding questions or concerns? It’s been a pleasure working with you on this issue, and I hope you are satisfied with the experience!