#73 Email with long lines (211 characters) rejected by exim 4

[Josh Soref]

Debian Stretch 9.8
Logwatch 7.4.3+git20161207-2
mailutils 1:3.1.1-1
exim4 4.89-2+deb9u3

Logwatch uses mailutils to send email to the local exim4
It accepts the email.
exim then connects to another exim4 instance:
Ubuntu bionic 18.04.2
exim4 4.90.1-ubuntu1.1

it rejected the email with a message: "message is too big (transport limit = 1)"

the line in question was a "Didn't Summarize: ... plain_server authenticator failed for very-long-reverse-dns.very-long.host ...", but the specifics don't matter.

[Bjorn]

This seems to be a problem particular to exim. One solution is to pipe the output destined for mail through fmt, by placing the following in /etc/logwatch/conf/logwatch.conf:
mailer = "fmt -s | /usr/sbin/sendmail -t"
The fmt program accepts other options.