I am new to doing mass mailings to customers and leads - not spam - and am looking for some introduction how to interpret different types of rejection messages so we can improve our success rate etc.
We are mailing from our own CRM system but using Ionos (1and1.com) as our mail service. I have set up SPF and DMARC but it is not possible to have DKIM signature with Ionos. Our recent mailing this week resulted in a bunch of rejection messages from outlook.com and later some rejections from mimecast that apparently some customers use for their mail handling. Two examples from outlook.com are (recipient xxxed out): SMTP error from remote server for RCPT TO command, host: xxx.mail.protection.outlook.com (104.47.51.202) reason: 550 5.7.1 Service unavailable, Client host [74.208.4.197] blocked using Customer Block list AS(1420) [AM7EUR03FT040.eop-EUR03.prod.protection.outlook.com 2023-05-05T06:31:14.035Z 08DB4D3079BE1687] and SMTP error from remote server for RCPT TO command, host: xxx.mail.protection.outlook.com (104.47.12.36) reason: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) [DB3EUR04FT050.eop-eur04.prod.protection.outlook.com 2023-05-05T06:31:00.028Z Example from mimecast (recipient xxxed out): Generating server: PAWPR05MB10142.eurprd05.prod.outlook.com *Diagnostic information for administrators:* x...@xxx.tld Receiving server: PAWPR05MB10142.eurprd05.prod.outlook.com 5/6/2023 2:39:35 AM - Server at PAWPR05MB10142.eurprd05.prod.outlook.com returned '550 5.4.316 Message expired, connection refused(Socket error code 10061)' 5/6/2023 2:30:01 AM - Server at edge.xxx.tld (104.18.43.156) returned '450 4.4.316 Connection refused [Message=Socket error code 10061] [LastAttemptedServerName=edge.xxx.tld] [LastAttemptedIP=104.18.43.156:25] [SmtpSecurity=-2;-2] [AM6EUR05FT032.eop-eur05.prod.protection.outlook.com 2023-05-06T02:30:01.780Z 08DB4DA7E366A32E](Socket error code 10061)' In order to improve delivery success rate after cleaning up old information in the CRM, I need to learn how to better interpret information like above. With the above said, the first kind of message from outlook.com seems to indicate we are on some kind of blacklist but what does the second outlook.com message tell me? That the recipeint is no longer with the company? Or something else? Thank you.
_______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
