SMTP IP whitelist in CIDR format

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Brett Rowbotham
Posts: 544
Joined: Mon Nov 03, 2003 7:48 am
Location: Cape Town

SMTP IP whitelist in CIDR format

Post by 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).

Cheers,
Brett

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

Re: SMTP IP whitelist in CIDR format

Post by nethub » Wed Aug 10, 2016 9:11 am

I agree with Brett.

Or alternatively MailEnable can support DNSWL (https://www.dnswl.org/?page_id=23) , just like qmail / postfix, so that we can setup own DNS to whitelist any IP.
Nethub Online Limited
https://www.nethub.com.hk

Brett Rowbotham
Posts: 544
Joined: Mon Nov 03, 2003 7:48 am
Location: Cape Town

Re: SMTP IP whitelist in CIDR format

Post by Brett Rowbotham » Wed Nov 18, 2020 5:51 am

Approaching 5 years later and still looking for this feature (my own post showing up on a Google search !).

Recently had to whitelist 8192 possible IP addresses. Could have been done with 9 CIDR entries, actually took 32 wildcard entries.

Please look into extending whitelisting to CIDR format to make it simpler to carry out this kind of task.

Cheers,
Brett

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