On Tue 09/Aug/2022 12:23:51 +0200 Tobias Fiebig via mailop wrote:
I am currently trying to debug a test for MTA-STS sending; The setup is a
domain with an MX with an invalid certificate to test whether MTA-STS policies
are honord (if they are, no mail should be received). I tested this last night
with an ESP I know should be honoring MTA-STS; However, while the policy was
retrieved from the webserver, the email got ultimately delivered. I also did
not get an MTA-STS TLS-RPT, even though other domains got them from the same
ESP today.
Could some of you who are on a setup that validates MTA-STS please try to send
me an email to, and if it (hopefully) fails share the NDR?:
[email protected]
Here's the warning I've received thus far, using Courier-MTA:
---------------------------------------------------------------------------
DELAYS IN DELIVERING YOUR MESSAGE
The delivery of the following E-mail message has been delayed. This is an
advisory notice only; it is sent only to notify you about a temporary delay
in delivering your message. You DO NOT need to do anything at this time.
Additional attempts to deliver your message will be made. Some possible
reasons for this delay:
* Network congestion or failure.
* The destination mail server is temporarily off-line.
Diagnostic information is provided below for each recipient. If copies of
this message were sent to additional recipients, deliveries to those
addresses are not included in this notice. This is an advisory notice for
the following addresses only:
<[email protected]>:
tls-invalid.measurement.email-security-scans.org [195.191.197.90]:
>>> STARTTLS
<<< 400 Invalid peer certificate
---------------------------------------------------------------------------
If your message was also sent to additional recipients, their delivery
status is not included in this report. You may or may not receive
other delivery status notifications for additional recipients.
The original message follows as a separate attachment.
--=_courier_0
Content-Type: message/delivery-status
Content-Transfer-Encoding: 7bit
Reporting-MTA: dns; wmail.tana.it
Arrival-Date: Wed, 10 Aug 2022 09:55:52 +0200
Received-From-MTA: dns; [172.25.197.111] (pcale.tana [172.25.197.111])
Final-Recipient: rfc822;
[email protected]
Action: delayed
Status: 4.0.0
Will-Retry-Until: Wed, 17 Aug 2022 09:55:52 +0200
--=_courier_0
Content-Type: text/rfc822-headers; charset="utf-8"
Content-Transfer-Encoding: 7bit
[DELETED]
--=_courier_0--
Best
Ale
--
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