[MM3-users] MM3 generates long lines?

I'm seeing emails being dropped when mm3 talks to the local smtp server, with log errors like:

2021-06-23 15:42:24 1lvvea-007r8u-VN H=localhost (<FQDN>) [::1] F=<announce-bounces@<FQDN>> rejected after DATA: maximum allowed line length is 998 octets, got 1036

The email itself did not have such long lines AFAICT.

I can disable line length checking on the mailserver, but that sounds like a recipe for the next one along to drop the email.

Peter C