I have a problem sending messages to customers who use protected.outlook.com
Sending usually ends with the error "451 4.7.0 Timeout waiting for client input" or "timed out while sending message body"
To other mail servers messages arrive without any problems.
I tried changing MTU, setting DF, but without success
Hi,
It would help to let us know what plan are you on with OVH.
Different plans have different options available to them.
If you are on the FREE plan see my post here:
https://community.ovhcloud.com/t/6565
If you are on the PAID e-mail plan, check out your have DKIM set-up:
https://help.ovhcloud.com/csm/en-ie-dns-zone-dkim?id=kb_article_view&sysparm_article=KB0058259
Also check your domain is set up correctly
https://mxtoolbox.com/
And your e-mail is compliant with current standards
https://www.1tester.com/tester.com/
DKIM, DMARC, SPF are fine. Not all emails have problems, but most (only to *.protection.outlook.com ). I turned on debugging in postfix per domain and I see in the log:<br />354 Start mail input; end with .<br />Some of the mails end correctly ( .), some unfortunately do not, with the message <br /> Nov 29 10:44:07 poczta postfix/smtp[24340]: < lexmark-<a target="_blank">com.mail.protection.outlook.com[52.101.40.1]:25:</a> 451 4.7.0 Timeout waiting for client input [CY4PEPF0000E9D0.namprd03.prod.outlook.com 2023-11-29T09:<br />Nov 29 10:44:07 poczta postfix/smtp[24340]: send attr diag_text = 451 4.7.0 Timeout waiting for client input [CY4PEPF0000E9D0.namprd03.prod.outlook.com 2023-11-29T09:43:07.402Z 08DBED3A0DB0934B]<br />Nov 29 10:44:07 poczta postfix/smtp[24340]: send attr mta_mname = 1com.mail.protection.outlook.comcom.mail.protection.outlook.com<br />Nov 29 10:44:07 poczta postfix/smtp[24340]: send attr reason = host 1com.mail.protection.outlook.com[52.101.40.1]com.mail.protection.outlook.com[52.101.40.1] said: 451 4.7.0 Timeout waiting for client input [CY4PEPF0000E9D0.namprd03.prod.outlook.com 2023-11-29T09:43:07.402Z 08DBED3A0DB0934B] (in reply to end of DATA command)<br />Nov 29 10:44:08 poczta postfix/smtp[24340]: DE33B100209: to=lexmark.com>, relay=lexmark-<a target="_blank">com.mail.protection.outlook.com[52.101.40.1]:25,</a> delay=74019, delays=73040/0.02/431/549, dsn=4.7.0, status=deferred (host 1com.mail.protection.outlook.com[52.101.40.1]com.mail.protection.outlook.com[52.101.40.1] said: 451 4.7.0 Timeout waiting for client input [CY4PEPF0000E9D0.namprd03.prod.outlook.com 2023-11-29T09:43:07.402Z 08DBED3A0DB0934B] (in reply to end of DATA command))