==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):
0.9.9 MARIADB edition.

- Deployed with iRedMail Easy or the downloadable installer?
Installer

- Linux/BSD distribution name and version:
Debian 9.8

- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
MySQL

- Web server (Apache or Nginx):
Nginx

- Manage mail accounts with iRedAdmin-Pro?
Yes

- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

We are using the server with local mailboxes but also as an outgoing relay server for some customers. So we activated postfix address verification for recipients (reject_unverified_recipient) in main.cf:

# Recipient restrictions
smtpd_recipient_restrictions =
    reject_non_fqdn_recipient
    reject_unlisted_recipient
    reject_unverified_recipient
    check_policy_service inet:127.0.0.1:7777
    permit_mynetworks
    permit_sasl_authenticated
    reject_unauth_destination

address_verify_map = btree:/var/lib/postfix/postfix_address_verify_map
unverified_recipient_reject_code = 550

This works fine for external mailhosts an even with the internal mailboxes. But if a mail is send to a local mail alias, the log states something like this:

Jun  6 11:45:32 mail postfix/smtpd[13998]: NOQUEUE: reject: RCPT from gw1.imagearts.de[80.82.217.141]: 450 4.1.1 <mailtest@lilabaer.de>: Recipient address rejected: unverified address: Address verification in progress; from=<nils.bernhardt@imagearts.de> to=<mailtest@lilabaer.de> proto=ESMTP helo=<gw1.imagearts.de>

The sending mail server keeps trying to deliver the mail, but iredmail always sais "Address verification in progress".

We also noticed that under normal cicumstances, nothing is logged in mail.log when a mail is delivered to a local alias.

Any ideas?