Final-Recipient: rfc822;<USER>@hotmail.com
Action: failed
Status: 5.2.3
Diagnostic-Code: smtp;552 5.2.3 This message is larger than the current system limit or the recipient's mailbox is full. Create a shorter message body or remove attachments and try sending it again.
So really I now have NO CLUE as to why or when the <CRLF> errors occur. Seems to be so random. I'm going to open a ticket to see what ME staff say...
MailEnable: Message Delivery Failure.
The following recipient(s) could not be reached:
[SMTP:<user>@hotmail.com]: 354 Start mail input; end with <CRLF>.<CRLF>
Apparently the <crlf> issue has now been fixed in Pro 1.18
From MailEnable Staff:
It looks like the connection is dropping out when sending the email data. Check the SMTP Debug log which will indicate the error code. There was changes in the 1.18 version to stop it sending an incorrect string to the client as a bounced email (it is sending the last response it got from the hotmail server)...