Hellow Benoît, Benoît Panizzon via mailop <[email protected]> writes:
> Hi Gang > > I was just able to reproduce a strange issue with an Outlook customer. > > Receiving end is Postfix with an Let's encrypt wildcard cert. As far > the cert looks valid, the chain looks ok. > > When the outlook customer is sending an email I see this in the logs: > > 2026-02-20T15:19:39.867675+01:00 mail postfix/smtpd[115462]: connect from > mail-westeuropeazlp170110003.outbound.protection.outlook.com[2a01:111:f403:c201::3] > 2026-02-20T15:19:40.034763+01:00 mail postfix/smtpd[115462]: disconnect from > mail-westeuropeazlp170110003.outbound.protection.outlook.com[2a01:111:f403:c201::3] > ehlo=1 starttls=1 quit=1 commands=3 > 2026-02-20T15:19:40.065412+01:00 mail postfix/smtpd[115435]: connect from > mail-westeuropeazon11021129.outbound.protection.outlook.com[52.101.70.129] > 2026-02-20T15:19:40.230800+01:00 mail postfix/smtpd[115435]: disconnect from > mail-westeuropeazon11021129.outbound.protection.outlook.com[52.101.70.129] > ehlo=1 starttls=1 quit=1 commands=3 > 2026-02-20T15:19:42.145161+01:00 mail postfix/smtpd[115462]: connect from > mail-westus3azlp170100009.outbound.protection.outlook.com[2a01:111:f403:c107::9] > 2026-02-20T15:19:42.947705+01:00 mail postfix/smtpd[115462]: disconnect from > mail-westus3azlp170100009.outbound.protection.outlook.com[2a01:111:f403:c107::9] > ehlo=1 starttls=1 quit=1 commands=3 > 2026-02-20T15:19:42.993766+01:00 mail postfix/smtpd[115435]: connect from > mail-westus3azon11020138.outbound.protection.outlook.com[52.101.201.138] > 2026-02-20T15:19:43.835172+01:00 mail postfix/smtpd[115435]: disconnect from > mail-westus3azon11020138.outbound.protection.outlook.com[52.101.201.138] > ehlo=1 starttls=1 quit=1 commands=3 > > So obviously outlook just send the three commands: ehlo, startls and quit but > never transmit the email. > > The sender is never getting a notification (issue persists for one week now) > about emails not being transmitted. > > Only emails sent from outlook customer are affected. > > Anyone else observing that issue and having an idea what the cause could be? Viktor already gave excellent advice in another thread. I just wanted to provide evidence that the relationship between Microsoft's mail server and Postfix for email delivery is not a problem. Here are two references [1-2] (I tested this with my personal email account): [1] mail logs: <https://gitlab.com/soyeomul/Gnus/-/raw/c6afccb1ab07f43eb17b3d6f2823a347b8f96d5f/stuff/outlook.log> [2] email full headers: <https://gitlab.com/soyeomul/Gnus/-/raw/c6afccb1ab07f43eb17b3d6f2823a347b8f96d5f/stuff/outlook.eml> And i am DANE user (DANE-TA 2 1 1). Sincerely, Byunghee
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