MAIL FROM AUTH=<> returns 501 Parameter AUTH is not recognised

[ddaymn]

When sending mails using outlook they are rejected

250-AUTH=CRAM-MD5 PLAIN LOGIN ANONYMOUS 250 AUTH CRAM-MD5 PLAIN LOGIN ANONYMOUS MAIL FROM:[email protected] SIZE=13343 AUTH=<> 501 Parameter AUTH is not recognised QUIT 221 Goodbye

[rnwood]

Hi. Thanks for reporting this.

Can you clarify which platform and version of Outlook this behaviour shows up with (or is this from web based outlook.com?). Also what settings do you have for the outgoing mail server authentication.

Thanks Rob

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From: ddaymn [email protected] Sent: Thursday, November 19, 2020 7:54:53 PM To: rnwood/smtp4dev [email protected] Cc: Subscribed [email protected] Subject: [rnwood/smtp4dev] 501 Parameter AUTH is not recognised (#565)

When sending mails using outlook they are rejected

250-AUTH=CRAM-MD5 PLAIN LOGIN ANONYMOUS 250 AUTH CRAM-MD5 PLAIN LOGIN ANONYMOUS MAIL FROM:[email protected]mailto:[email protected] SIZE=13343 AUTH=<> 501 Parameter AUTH is not recognised QUIT 221 Goodbye

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[ddaymn]

It is outlook.com in general. My thought is that it is the empty AUTH<> I see other messages that work but there are values in between the <>. That value above was from the session log in smtp4dev. I do not have SMTP relay enabled.

[rnwood]

I've had a look at web based Outlook (there's several apps branded as this by MS).

Can you confirm you are referring to the app at https://outlook.live.com/ (not the O365 one at outlook.office.com) and specifically that this can be reproduced using these settings to get it to send outgoing messages via SMTP: