Message has lines too long for transport ошибка

Today I got a message from a customer who experienced the same on a centos 7.9.2009 server.

Is there a step by step instruction on how to downgrade?

customer who experienced the same

What is the error ?

@cDGo
maybe this conf can help you
«message_linelength_limit=2048» //2048 is for test purpose, default value are 998

try adding to «/etc/exim.variables.conf»
and restart exim

if fixed issued, add it to «exim.variables.conf.custom»

Sorry, I wrong reading from change log
not for global config, It should for smtp transport option

Example: put directly into remote_smtp:
inside exim.conf

this’s your problem, it relate to «message_linelength_limit» ( Line 5054 )

this version, I still learning some future/update too

Hi jamgames2,

Thanks for looking into it again.
I’m afraid, I’m not sure what you want me to do.

In exim.conf I’ve got no reference to remote_smtp at all.
So Should I add it and where?
And what value to use?

@cDGo

remote_smtp:
driver = smtp
headers_add = «${if def:authenticated_id{X-Authenticated-Id: ${authenticated_id}}}»
interface = <; ${if exists{/etc/virtual/domainips}{${lookup{$sender_address_domain}lsearch*{/etc/virtual/domainips}}}}
helo_data = ${if exists{/etc/virtual/helo_data}{${lookup{$sending_ip_address}iplsearch{/etc/virtual/helo_data}{$value}{$primary_hostname}}}{$primary_hostname}}
message_linelength_limit = 2048
.include_if_exists /etc/exim.dkim.conf

if im not wrong, should be like this.
2048 is for test, it upto you, too much value can be security issued

If Outlook doesn’t count line lengths right, I think it would make sense for CustomBuild to increase the line length limit in Exim to something more than 998 during build. We’re seeing customers having this issue as well now (with Reference: header).

This is not SMTP compliant solution, so I think it is not recommended to set it as ‘default’ + each user can adjust maximum length value.

Ideally Exim team should implement builtin line folding, something like Postfix already has.
Line length exceeds maximum length? Add CRLF + space after x characters. This is 100% valid solution.
Currently there is possibility to implement it as transport_filter in e.g C++, but dealing with input, that can reach hundreds of megabytes is not pleasent.

We are also getting the lines too long error with Exim 4.95, this was not an issue in Exim 4.94.2:

Workaround: downgrading to Exim 4.94.2:

echo "exim:4.94.2:" >> /usr/local/directadmin/custombuild/custom_versions.txt
/usr/local/directadmin/custombuild/build update
/usr/local/directadmin/custombuild/build exim

So, for those of us getting the «message has lines too long for transport» error — is the consensus that we downgrade to 4.94.2? I’ve just gotten a few complaints from one client who uses Outlook. Their parent organization uses Microsoft 365 and my client is now unable to send email them.

Are there any security implications to downgrading?

So, for those of us getting the «message has lines too long for transport» error — is the consensus that we downgrade to 4.94.2? I’ve just gotten a few complaints from one client who uses Outlook. Their parent organization uses Microsoft 365 and my client is now unable to send email them.

Are there any security implications to downgrading?