Today I would like to point out something that drove me crazy for over a week. A customer called us regarding some messages being generated from a server, let's call it SERVER1, and sent through smtp relay configured in Exchange, were being received with blank content (no email body). At first I though to myself... "Oh my god, here comes another end-user Outlook problem", but after I tried it myself, I saw that no matter what client you tried to open the message with, outlook, gmail, or any other web or installed client, all the emails sent from this server were completely blank.
I tested it myself with the following:
220 internal.relay.domain.com Microsoft ESMTP MAIL Service ready at Tue, 9 Jul 20 13 13:05:46 +0200 helo mydomain.com 250 internal.relay.docout.es Hello [172.28.0.35] mail from: email@example.com rcpt to: firstname.lastname@example.org 250 2.1.5 Recipient OK data 354 Start mail input; end with <CRLF>.<CRLF> to: email@example.com from: firstname.lastname@example.org subject: subject from SERVER1 This is my content . 250 2.6.0 <5cf64727-f4bf-44ca-a084-e4e4d432964b@SERVER1.domain.com> [Internal Id=3365140] Queued mail for delivery quit 221 2.0.0 Service closing transmission channel
Sure enough, just as customer said, this mail was received with blank contents instead of the "this is my content" text.