The situation is:
- domain.tld has an MX mx.anti-spam-operator.tld;
- there are no other MX records;
- server mx.anti-spam-operator.tld sends EMail messages to mx.hosting-provider.tld (EMail accounts at domain.tld are here);
- mx.hosting-provider.tld software: Ubuntu 14.04.1, ISPmanager Lite 5.104.5, Exim 4.82...
...But there are no EMail messages in mailboxes.
Here is the simplest test
====
user@mx.hosting-provider.tld:~$ telnet mx.hosting-provider.tld 25
Trying 8.16.32.64...
Connected to mx.hosting-provider.tld.
Escape character is '^]'.
220 mx.hosting-provider.tld ESMTP Exim 4.82 Ubuntu Wed, 27 Sep 2017 12:01:17 +0300
ehlo mx.hosting-provider.tld
250-mx.hosting-provider.tld Hello mx.hosting-provider.tld [8.16.32.64]
250-SIZE 52428800
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN CRAM-MD5
250-STARTTLS
250 HELP
mail from:
donald@trump.me
250 OK
rcpt to:
walter_white@domain.tld
250 Accepted
data
354 Enter message, ending with "." on a line by itself
Subject: Test
Test.
.
250 OK id=1dx8Dw-000CZC-KI
quit
221 mx.hosting-provider.tld closing connection
Connection closed by foreign host.
====
2017-09-27 12:02:10 1dx8Dw-000CZC-KI <=
donald@trump.me H=mx.hosting-provider.tld [8.16.32.64] P=esmtp S=1379 from <donald@trump.me> for
walter_white@domain.tld
2017-09-27 12:02:10 1dx8Dw-000CZC-KI **
walter_white@domain.tld R=dnslookup T=remote_smtp: SMTP error from remote mail server after initial connection: host mx.anti-spam-operator.tld [16.32.64.128]: 550 Connection refused
2017-09-27 12:02:11 1dx8EN-000Caf-0B <= <> R=1dx8Dw-000CZC-KI U=Debian-exim P=local S=2298 from <> for
donald@trump.me
2017-09-27 12:02:11 1dx8Dw-000CZC-KI Completed
====
Anti-spam operator's support confirm that messages are
sent to and
accepted by mx.hosting-provider.tld.
I have logs from mx.anti-spam-operator.tld of transfer of messages from external servers, other domains, etc. (not from localhost to localhost like in the example above, it's a simplest example I've achieved).
That logs are normal, here are first three and last five lines
Wed 2017-09-27 10:57:15: Session 27; child 1
Wed 2017-09-27 10:57:13: Parsing message <c:\mdaemon\remoteq\pd50013882648.msg>
Wed 2017-09-27 10:57:13: * From:...
Wed 2017-09-27 10:57:13: Transfer Complete
Wed 2017-09-27 10:57:15: <-- 250 OK id=1dx7DW-0009qG-Ea
Wed 2017-09-27 10:57:15: --> QUIT
Wed 2017-09-27 10:57:15: <-- 221 mx.hosting-provider.tld closing connection
Wed 2017-09-27 10:57:15: SMTP session successful (Bytes in/out: 376/452
The result is the same: "R=dnslookup T=remote_smtp: SMTP error from remote mail server after initial connection: host mx.anti-spam-operator.tld [16.32.64.128]: 550 Connection refused".
====
You can copy to your favorite search system long requests:
when the server is going to send a email exim makes a nslookup and get the higher priority (lower value) MX record and tries to send the mail to the asigned address
MX records of equal priority are sorted by Exim into a random order. Exim then looks for address records for the host names obtained from MX or SRV records. When a host has more than one IP address, they are sorted into a random order, except that IPv6 addresses are always sorted before IPv4 addresses.
====
The question is predictable: how to make mx.hosting-provider.tld just to put messages in mailboxes (without making DNS requests, selecting MX and
forward EMail messages)?
I have been searching the answer about ten hours with no success.