Verify Receivers

[bct]

Hi there,

If the exchange server is taken down for maintenance or repairs, how does the “Verify Receivers” feature handle this situation?

Does it accept all or reject all?

Thanks!
BCT

 

[tom]

Hi there,

If the exchange server is taken down for maintenance or repairs, how does the “Verify Receivers” feature handle this situation?

Does it accept all or reject all?

Thanks!
BCT

Hi,

Verify Receivers has two option: Yes 550, and Yes 450.

550 means, the sender to non-verified receivers gets a FINAL error message, 550.

450 means, they get a temporary unavailable and I think this is what you need if your internal mail server is not available. All RFC compliant senders will try again later, maximum normal one week - Your exchange should be online again within this timeframe.

 

[dietmar]

hi bct,

"When verification takes too long the Postfix SMTP server defers the recipient address with a 450 reply."

We suggest to use the 'Yes 450' setting for testing. Change this setting into 'yes 550' when you trust Proxmox judgments. Proxmox always replies with 450 when the final destination is not reachable.

Best regards,

Dietmar

 

[DerDanilo]

How does the recipient caching work?

Is it currently possible to specify the recipient target? It would be nice to be able to set e.g. an LDAP, SMTP, IMAP backend or other means of verification targets, as well as the timeframe that the system caches existing recipients.

 

[dietmar]

We use the postfix feature 'Receiver Verification' as described in:

http://www.postfix.org/ADDRESS_VERIFICATION_README.html

See http://www.postfix.org/verify.8.html for option to control the cache.

 

[DerDanilo]

According to the default config in PMG this is:

root@pmg1:/# postconf -d | grep -i 'address_verify_positive_'
address_verify_positive_expire_time = 31d
address_verify_positive_refresh_time = 7d

I guess you keep the default settings then, correct?

 

[dietmar]

I guess you keep the default settings then, correct?

yes

 

[masterx]

Hi,

another resurrection of this old thread... Wouldn't it be cool to have recipient validation rely on LDAP/Active Directory information optionally, so you don't have to have Exchange Recipient Validation enabled which is kind of janky (having to use a different transport connector on port 2525)?

One of the reasons for a mail gateway in front of Exchange servers always was that you don't have to deal with the Exchange quirks anymore and it would be really nice if PMG could pull valid recipients from LDAP/Active Directory optionally...

 

[masterx]

Hi,

another resurrection of this old thread... Wouldn't it be cool to have recipient validation rely on LDAP/Active Directory information optionally, so you don't have to have Exchange Recipient Validation enabled which is kind of janky (having to use a different transport connector on port 2525)?

One of the reasons for a mail gateway in front of Exchange servers always was that you don't have to deal with the Exchange quirks anymore and it would be really nice if PMG could pull valid recipients from LDAP/Active Directory optionally...

like... it wouldn't even be THAT hard to implement. fetch all users from AD, get the email attribute and the attribute which contains all the aliases, make these two fields customizable to be compatible with other systems than MS AD DS and boom, done.