Forum Discussion

Copper Contributor

Oct 22, 2018

Solved

External exchange port 25 once all mailboxes are moved..

Hi, We have moved all our mailboxes to Office 365. Our MX records point to Office 365. Is there any reason to have the external port 25 open on our in house Hybrid server? Thanks

hybrid

office 365

On-Premises

adam deltinger
Oct 22, 2018
Ok, if you’re not using on premises mail servers (hybrid) you’re safe to block it :)

Cheers / adam

adam deltinger

MVP

Oct 22, 2018

Probably not if you’re not running any devices or applications with smtp submission on port 25 ( not recommended ) some legacy devices and apps don’t support recommended port 587 for this and may use port 25!

Adam

Bill Lohrer
Copper Contributor
Oct 22, 2018
Just to be clear when you say "running any devices or applications with smtp submission on port 25" you mean external devices or apps, Correct?

That I know of we are not running any.

Thanks
- adam deltinger
  MVP
  Oct 22, 2018
  I mean for example devices like MF printers sending out mails to people! A common way for this is to use smtp to send, but most devices today is using port 587 for this!
  - Bill Lohrer
    Copper Contributor
    Oct 22, 2018
    an MFP printer would be internal to our network. I am looking at the old inbound port 25 that email came into.