Hi Gang Very strange observation with a Office365 customer.
We have separate ip addresses for MX and submission. MX => Obviously only accepting emails for local recipients. Submission => Requiring SMTP authentication to send emails no matter what destination. With a customer with his own domain and business Office365 subscription we observe this scenario: Office365 customer sending a 'new' email to one of our customers. => Email hits MX IP and is delivered to local mailbox. Our customer sending an Email to Office365 customer. Email leaves from our 'submission' IP address hits MX of outlook.com. Office365 customer now REPLIES to this email he just received. REPLY is hitting the 'submission' ip address (not the MX of the recipient domain) does not authenticate and of course is getting 'relaying denied'. It looks like as if Office365 is sending the reply back to the IP it originally got the email from and ignores the MX for the recipient domain. This does not happen all the time. Only with certain emails, not sure yet what the trigger is. Does someone know if this is a Bug or misconfiguration on the Office365 plattform? Mit freundlichen Grüssen -Benoît Panizzon- -- I m p r o W a r e A G - Leiter Commerce Kunden ______________________________________________________ Zurlindenstrasse 29 Tel +41 61 826 93 00 CH-4133 Pratteln Fax +41 61 826 93 01 Schweiz Web http://www.imp.ch ______________________________________________________ _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
