Graylisting with O365 Mailboxes

Discussions on webmail and the Professional version.
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Joined: Tue Jan 16, 2018 1:30 pm

Graylisting with O365 Mailboxes

Post by dmatesic » Wed Dec 19, 2018 2:27 pm

Hi, i have many problems when graylisting is turned on and the sender is using an Office 365 service hosting custom user domain.
There are long delays, sometimes the message is not delivered for days.
O365 has a range of few hundreds IP addresses and it's impossible to add them one by one using files or manually in the SMTP allowed list.
Similar to gmail hosting custom domain.
If i turn off the graylisting i am afraid that i will start to get random mail messages and that the SPAM rate will be increased.
So, what can be done?
Can the MailEnable team include in the product the lists of Google and Microsoft outbound IP ranges?


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Re: Graylisting with O365 Mailboxes

Post by Admin » Thu Jan 03, 2019 4:11 am


Office365 I think has over 500k IPs valid in their range, so it's not possible to whitelist them individually, and there is no CIDR exceptions available for greylisting. What you need to do is to add the domains themselves to the whitelist for greylisting, since it will use their SPF record to validate them. Unfortunately it has to be done on a domain basis at the moment.

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