Failed to reach server when use reply

[panthera]

Im sending mails with no problems, replying no problems, BUT when i reply to e-mail that has for exapmle pictures in signature i got "Failed to reach server" error


but when i delete this signature with images, tables and so on it goes through.
how do i fix it.


thnx

[SKaero]

What does the Roundcube and web server error logs say?

[alec]

Typically it is a Wordfence or mod_security on the HTTP server. Logs should tell you that.