Office 365 Exchange Online email servers


I´m configuring my firewall allowing from my network SMTP 587, POP3 or SMTP to any meanwhile I find which destinations use Office 365 but I cannot find this info.

Where can I fin info about this?

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Damien KayCommented:
The published list above is long, and not really manageable.  I'd suggest you may not need to open all those ports.
Your Outlook Clients and ActiveSync devices will all use port 443 with Office 365, and this port is probably already open "ANY to ANY"
POP3 (110/995) and SMTP (25/465) are almost never needed anymore.
Only your Scanners and similar devices should need Port 587, not all your clients. Opening Port 587 for "some to ANY" is not a high security risk.
I usually add both an internal and an external DNS CNAME record that points "" to the external MX record for the O365 domain, for ease of use.
That way, you may be able to write your firewall rule for Outbound Port 587 as "some to"
Of course, if you have other older clients, you may want those ports...

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heze54Author Commented:
Nice posts!!
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