Allowed IP Address ranges for SMTP services
Posted by Helpdesk Admin on 27 July 2009 10:13 AM

If you operate a firewall that blocks inbound SMTP email on port 25, you may need to open access on this port to the following IP addresses in order to ensure proper mail delivery to your in-house mail server. In the case of Spam Filtering services, you may wish to only allow the relevant ranges from the filtering servers and block all senders to prevent emails bypassing the filtering servers. 

MX Backup and SpamFilter.ie 

Configure your firewall to accept email connections from mail servers at delivery.antispamcloud.com or else allow connections from IP addresses with a PTR record of the form  *.antispamcloud.com

Alternatively, it may be more convenient to configure your email server to accept inbound connections on a non-standard port (e.g. 2525) and allow connections from all addresses on that port (please ensure the spam filter is configured to deliver to this new port number).

Postini (Discontinued from June 2013) 

64.18.0.0/20

Broadcom/Symantec.cloud/Messagelabs (replacing Postini from June 2013)

216.82.240.0/20
67.219.240.0/20

85.158.136.0/21

95.131.104.0/21
46.226.48.0/21

117.120.16.0/21
193.109.254.0/23

194.106.220.0/23
195.245.230.0/23
103.9.96.0/22

If you run your own connection time spam filtering on your email server, we recommend that you additionally whitelist all the above ranges in your system, in order to prevent false positives or other relaying issues.

This is especially important for MX backup as otherwise automatic relaying of messages after an outage may not happen reliably.


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