Call external script upon mailbox or alias creation

ecdlguy

Hi,
Is it possible to call a script upon mailbox or alias creation?
I’m asking because I need to whitelist (via a HTML Post) every address on our inbound mail gateway.
cheers, Thorsten

esackbauer

ecdlguy whitelist (via a HTML Post) every address on our inbound mail gateway.

What?
That inbound mail gateway cannot to do callback verification?
https://en.wikipedia.org/wiki/Callback_verification
Mine can, so I do not need such a workaround.

DocFraggle

You can use the API to retrieve all mailboxes, just add /api to your mailcow instance

Example:

https://demo.mailcow.email/api/#/Mailboxes/Get%20mailboxes

This way you could run a cron job to update your whitelist

ecdlguy

esackbauer That inbound mail gateway cannot to do callback verification?

There are several servers in front, including servers of our university computer center.
I can only guess, but either they decided against callback verification or they just don’t know that it’s possible ;-)
However I’m going to ask them. Would make things easier. Also, at the moment it takes an unpredictable amount of time until the address is not rejected after adding it to the whitelist. I guess this is due to a cronjob.

@DocFraggle thanks for the suggestion!

ecdlguy

esackbauer
I’ve been thinking about this a bit more, maybe we are not talking about the same thing.
Sender address verification is happening at our inbound mail gateway.
The purpose of the whitelist is to check the eligibility of the recipient, i.e. check if the recipient exists on the final destination mail server with the mailbox.
With regard to the Wikipedia article you mentioned there seems to be something referred to as “call forwards”:

A related technique is “call forwards”, in which a secondary or firewall mail exchanger can verify recipients at the primary mail exchanger for the domain in order to decide whether the address is deliverable.

cheers,
Thorsten

esackbauer

Recipient Address verification (also known as “Callout” or Call forward ), which is what you described as “check the eligibility of the recipient” can be cascaded over several MTAs if they support it, should not take longer than fractions of a second, if the MTAs in the chain trust each other. Or you have some internal greylisting 😉

If you have a proper mail gateway, it is also possible to check for eligible mail addresses via Active Directory or LDAP. Then you would not need the callback verification.

ecdlguy

@esackbauer Thanks again 👍️