Hi
We have a sophos running on SFOS 17.5.9.
To increase security we have limited the networks that are allowed to send traffic on port 25 and 587 to our cloud anti spam protection and now recently also exchange online since we created a hybrid exchange environment.
Unfortunately despite allowing the necessary IP ranges emails being sent directly from office 365 are sometimes being blocked. On some days it just works on others our email messages are getting stuck in Exchange online stating that the connection is refused. Changing allowed networks on port 25 and 587 solves that problem but is far less secure.
We have allowed all of the FQDN hosts and IP ranges below but are still running into connection refused messages.
We allowed the following FQDN hosts
*.office365.com
*.office.com
*.outlook.com
*mail.protection.outlook.com
*protection.outlook.com
And IP ranges
40.92.0.0/255.254.0.0
40.96.0.0/255.248.0.0
40.104.0.0/255.254.0.0
52.96.0.0/255.252.0.0
131.252.33.215/255.255.255.255
132.245.0.0/255.255.0.0
150.171.32.0/255.255.252.0
191.234.140.0/255.255.252.0
204.79.197.215/255.255.255.255
40.107.0.0/255.255.0.0
52.100.0.0/255.252.0.0
104.47.0.0/255.255.255.0
52.238.78.88/255.255.255.255
13.107.6.152/255.255.255.254
13.107.18.10/255.255.255.254
13.107.128.0/255.255.252.0
23.103.160.0/255.255.240.0
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