On 05/06/2023 02:17 PM, Dan Lester wrote: > You might want to explore the extent to which ionas might be sending these > out with IPs that are spam blacklisted. I just fought off a similar issue > with Sender, because they did assign me such an IP. I've also always > suspected that IPs are blocked not because they are currently blacklisted, > but because they have some history of blacklisting. My understanding is that > Microsoft is especially fierce about such things. > > > On 5/6/23 10:28 AM, H via mailop wrote: >> >> 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:* >> >> [email protected] >> >> 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 >> [email protected] >> https://list.mailop.org/listinfo/mailop > I just checked the Ionos IP address used for sending and it is not listed on any blacklists according to mxtoolbox.com and a couple of other sites. I also visited sender.office.com which prompted me to enter my email address and the IP address for delisting - it did not tell me if it was blacklisted or not though. Once submitted I received an email link which when clicked told me that my request to have it delisted was denied and did I want to escalate it. I confirmed so let‘s see.
It seems you are correct, outlook.com has a more aggressive blacklisting list.
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