Error on DATA input when sending mail over SMTP

[djas19]

When trying to send an email with swaks or over telnet/netcat the maildemon sees response code 354 as an error.

Very similar to this: https://serverfault.com/questions/509464/error-message-not-sent-server-replied-354/509469#509469

=== Connected to localhost.
<-  220 37f364021e15 ESMTP
 -> EHLO maildev-69cb
<-  250-37f364021e15 Nice to meet you, [172.XX.X.X]
<-  250-PIPELINING
<-  250-8BITMIME
<-  250 SMTPUTF8
 -> MAIL FROM:<user@maildev-69cb>
<-  250 Accepted
 -> RCPT TO:<user@example.com>
<-  250 Accepted
 -> DATA
<-  354 End data with <CR><LF>.<CR><LF>
 -> Date: Thu, 15 Feb 2024 17:29:12 +0100
 -> To: user@example.com
 -> From: user@maildev-69cb
 -> Subject: test Thu, 15 Feb 2024 17:29:12 +0100
 -> Message-Id: <20240215172912.028017@maildev-69cb>
 -> X-Mailer: swaks v20201014.0 jetmore.org/john/code/swaks/
 -> 
 -> This is a test mailing
 -> 
 -> 
 -> .
*** Remote host closed connection unexpectedly.

Reproduce by:
swaks --to user@example.com --server localhost:1025