Sendmail error

The e-mails shown below are not delivered to our mailservers. The logging shows that the messages are discarded with an error:

It is the same error that they reported earlier.
The mail subject contains a 0A (line feed) at the beginning, which causes the problem:

Thank you for looking into the issue. We are aware that you cannot change the behavior of Sendmail. But when the mail is released from the Mail Archiver, the mail is delivered correctly. So somehow releasing the message again does fix the problem. Maybe you could use that function somehow as a workaround.

Also, when the mail has been ‘delivered’ but dropped (Send mail error message) in the background, we have no way to see/sort the dropped messages to (manually) release them again. Is it possible to look into a new column or filtering feature to be able to quickly show all the dropped messages? Or do you have any other suggestion for recognizing the not-delivered mails?

The message is delivered correctly when released from the mail archiver because it doesn't rely on the qf file, which is deleted once the message has been stored to the mail archiver and delivered to the recipient.

They talk about this issue as a side effect generated by a fix to another issue, so it has been reverted