[MlMt] Strange "Delivery Status Notification (Failure)"

[Bill Cole]

On 4 Jul 2018, at 11:27 (-0400), Compass Luca Cignacco wrote:

> Today I’m having strange a behaviour of MailMate. When sending 
> emails to a supplier I get this error:
>
>     Action: failed
>     Status: 5.6.1
>     Diagnostic-Code: smtp;554 5.6.1 Body type not supported by Remote 
> Host
>
> I don't know whose fault that was, me or their servers?

Both.

I assume that text is coming in an email "bounce" notification. Usually 
such messages include other useful details about which machine replied 
with that "Diagnostic-Code" message, which indicates that you probably 
need to send your mail in a more traditional form: try pure plain text.

Technically, this is probably because your outbound mail server provides 
support for one of the mechanisms that let senders skip Base64 or 
Quoted-Printable encoding of anything other than 7-bit ASCII characters 
(there are actually 3: SMTPUTF8,  8BITMIME, and BINARYMIME.) MailMate 
will send "raw" 8-bit message parts if possible, but since not all mail 
servers support one or more of those transport extensions, it may not be 
possible for your immediate outbound server to hand the message off to 
the next hop.


-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Currently Seeking Steadier Work: https://linkedin.com/in/billcole