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Microsoft hosted Exchange internal relay to cPanel pop (and dns) mail loop

Discussion in 'E-mail Discussions' started by Arion, Jul 14, 2016.

  1. Arion

    Arion Registered

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    Awaiting root access to cPanel server. Full access on cPanel.

    Goal: Creating a hybrid environment where mail first gets routed to Microsoft hosted exchange, exchange takes what is has active boxes for, and then passes the rest to the cPanel server.
    Users who have exchange use exchange.
    Users who do not have exchange have ssl-pop and ssl-smtp via cPanel.
    All on the same example.blah domain.

    Working systems:
    All externally sent email gets routed to exchange, all mail exchange does not have boxes for is sent via a connector using TLS to the cPanel box. Users who have exchange use exchange receive their mail, and users who do not have exchange send/receive via cPanel.
    Outgoing mail sent via exchange and cPanel goes out.

    Problem:
    Currently users who send email via SSL-SMTP to the cPanel server to internal (same example.blah domain addresses) will have their mail delivered to the recipients cPanel box, not exchange.
    As soon as I tell cPanel to route mail via dns it creates a loop. Route internally and it does not correctly forward to exchange, all mail sent via smtp goes internal, exchange box or not.

    Also note:
    cPanel handles the DNS. Microsoft required DNS records on cPanel DNS.
    SPF includes both MS and cPanel domains. (learned the hard way, SPF of BOTH)
    Many users sending to cPanel ssl-smtp and scooping ssl-pop, initial roll out of exchange is executives only
    Users who have exchange still have cPanel mailboxes too.
    Microsoft hosted domains all have a example.onmicrosoft.com alias. (default)
    cPanel version 56.0.25

    What is the best solution ?
    Do all cPanel mail users have to use a alternate SMTP server to correctly route mail first to exchange without creating a loop ? (many user devices to reconfigure, some roaming abroad)

    Should I rather move the DNS hosting to Microsoft so when mail hits cPanel box it accepts instead of routes ? (This domain has crazy long dns, many many domain names, websites.)

    Can I get the cPanel box to treat mail coming in from users on SMTP one way (route via DNS) and mail sent from Microsoft via a connector (currently TLS) another (get routed internally to their boxes) ?

    Should I convert all the users who switch to Microsoft, on cPanel, from a mail box to alias pointing to their respective person@example.microsoft.com address ? (thinking this may be the most elegant method.)

    IS there some other solution that I have not thought of or come across in my searches on Google ?
     
  2. Arion

    Arion Registered

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    I added forwarders on the cPanel for each exchange box to forward to the example.onmicrosoft.com alias.

    It works well.

    I not have cPanel and Exchange running side by side and playing nice.
     
  3. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    I'm happy to see it's now working well. Feel free to post the specific steps you took to get this working for other users who face the same problem.

    Thank you.
     
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