Office 365 Hybrid Lock Down


  • Hi All,

    I have a local Exchange server 2013 which hosts a few different domains.  I have a Hybrid Connection setup for my main company domain and currently have two MX records the first one points to Office 365 which routes all email via online so we can leverage the excellent spam filtering.

    Because we have a secondary MX record which points to the server which I cannot get rid of for reasons that do not matter at this time we get quite a bit of spam that comes in via the secondary MX record to the servers SMTP address.

    What I would like to know; is there something I can do to lock down the SMTP connector on the server to only accept connections from Office 365 servers (maybe TLS) but only lock this down for one domain so the other can continue to operate normally?

    Thanks for any advice.

    Wednesday, October 14, 2015 9:59 AM