SMTP IP whitelist in CIDR format

Brett Rowbotham
Posts: 510
Joined: Mon Nov 03, 2003 7:48 am
Location: Cape Town

SMTP IP whitelist in CIDR format

Postby Brett Rowbotham » Wed Jan 27, 2016 4:57 am

Whitelisting IP addresses in the SMTP settings allows the use of wildcards. I need to whitelist all the IP addresses that Google Apps can use for email. This amounts to over 223 000 addresses and is virtually impossible to cover using only wildcard entries.

If CIDR format was available to specify the IP ranges to whitelist, then only 12 entries would be required to cover all the IPv4 addresses currently in use by Google Apps (and only 6 more if IPv6 was required).


Posts: 28
Joined: Sat Aug 01, 2009 5:55 pm

Re: SMTP IP whitelist in CIDR format

Postby nethub » Wed Aug 10, 2016 9:11 am

I agree with Brett.

Or alternatively MailEnable can support DNSWL ( , just like qmail / postfix, so that we can setup own DNS to whitelist any IP.
Nethub Online Limited

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