On 5/22/2025 3:33 PM, Wietse Venema via Postfix-users wrote:
To be precise, Postfix delivers the message with the 'good' display
name in the From: header. The unexpected change happens after Postfix
has delivered the message to some other system.
Maybe Azure SMTP is doing something to the message. I am not sure.
The chain is:
Thunderbird > Postfix -> Microsoft cloud > your mail user agent
The change could happen in Microsoft cloud, or in your
mail user agent.
Maybe your mail user agent (Thunderbird?) is overriding the display
name when it does not match the email address in the address book.
That cloud be a security feature.
I agree. At this point, it seems it is happening in Azure SMTP. Results
are the same no matter the client.
That's the same one as logged by Postfix, and confirms that
this is message matches the Postfix logging.
Now for the ultimate Irony. Azure SMTP has a daily limitation we could
exceed. Normal Office 365 Basic Auth email services are going EOL, so
they push you to "High Volume Email" services which is really still part
of O365. HVE has the same restrictions as Azure, but also DOES check the
header from address. If it isn't the specified account address, it
rejects it with a very clear message. So, I ironically now do have to
use a header check. I was close, but I couldn't get it to work
correctly. I wanted to rewrite the header from address but keep the
display name. I was about to post here, but tried ChatGPT instead. It
took refining the question a few times, but wow. That is really cool
that is gave me this.
/^From: (.*<).*@.*(>)/ REPLACE From:
${1}carespot-donotre...@carespot.com${2}
Weitse, Victor, and others. It is awesome that you still support this
project at this level. I was a heavy user from about 2005 to 2012, but
work took me down another path. It was too funny to immediately see an
email about a pflogsumm update after 11 years. It took about the same
break I did. Great stuff and impressive dedication and longevity.
Thanks,
Matthew
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