I sent an email to our BT account manager. I attached two call recordings. The message size in total was only about 30MB. Our mail systems regularly deal with multi-hundred MB attachments. I’m not even sure they have a limit as such.
SMTP error from remote mail server after MAIL FROM:<firstname.lastname@example.org> SIZE=44091640: host smtpb1.bt.com [220.127.116.11]: 552 5.3.4 Message size exceeds fixed maximum message size
Well thank you so much for that helpful, informative message, BT. Tell me it exceeds some mythical maximum size, but don’t tell me what that magical size is. Sigh.