Sendmail+Cyrus IMAP "Data format error" and bounces

[Deborah Pickett]

On 2020-03-28 04.59, Andrea Venturoli wrote:
> Any idea for a similar tool which can use UTF8SMTPS, so I can repeat
> that tests? 
I would be going low-tech and using telnet or netcat or socat to
converse directly with your mail server's port 25.  Craft the client's
side of the conversation in another window and copy-paste lines directly
to the SMTP service.  This way you can tweak the exact conversation and
hopefully trigger the behaviour you are intermittently seeing.