Setting up an internal relay from one exchange forest to another. E-mail is flowing fine from a to b and going to the correct mailbox. The problem lies in sending from the mailbox in domain b with domain a address on it. Domain B uses Office 365 SPAM filter and when a message is sent out from domain A from Domain B it blocks it. We added domain A to the domain list on 365 and it seemed to fix it. Then after a few hours anyone sending to domain A from domain B were getting bounce backs (error below) : I'm guessing it is as simple as not setting the SPF record correctly to allow mail from domain a to be allowed to originate from domain b? Once I migrate all users from Domain a to b I will redirect the MX record to point to office 365 but I want to keep it where it is for now. Anyone have any experience with this?
cas1.domainb.com #<cas1.domainb.com #5.7.1 smtp;550 5.7.1 Unable to relay> #SMTP#Original message headers:
Received: from sever.protection.gbl (xxx.xxx.xxx.31) by
BN1BFFO11HUB039.protection.gbl (xxx.xxx.xxx.186) with Microsoft SMTP Server
(TLS) id xxx.xxx.xxx.14; Tue, 19 May 2015 01:42:55 +0000
Authentication-Results: spf=permerror (sender IP is xxx.xxx.xxx.17)
smtp.mailfrom=domainb.com; domaina.com; dkim=none (message not signed)
header.d=none;
Received-SPF: PermError (protection.outlook.com: domain of domainb.com used an
invalid SPF mechanism)