Some messages are not delivered to @yandex.ru @rambler.ru addresses

Question

Exim

Hello!

There is an online store that sends 1-2 letters per minute (thank you for the order, your order has been completed, etc.).
Clients with mailboxes @rambler.ru @yandex.ru (and only from them!) constantly complain that the letter did not reach them. And some get it, some don't. If it didn't arrive, there are no messages in spam.

The server is Debian 5 Lenny, the STMP server is: exim4.

sudo grep rambler.ru /var/log/exim4/mainlog

Gives a long list of such errors:

2010-12-07 15:22:27 1PPwYq-0002i5-KM SMTP error from remote mail server after DATA: host imx1.rambler.ru [ 81.19.66.234]: 452 4.7.1 Try again later
2010-12-07 15:22:28 1PPwYp-0002i0-Ah SMTP error from remote mail server after DATA: host imx1.rambler.ru [81.19.66.235]: 452 4.7 .1 Try again later
2010-12-07 15:22:28 1PPwYp-0002i0-Ah SMTP error from remote mail server after DATA: host imx2.rambler.ru [81.19.88.3]: 452 4.7.1 Try again later
2010-12-07 15: 22:29 1PPwYp-0002i0-Ah SMTP error from remote mail server after DATA: host imx2.rambler.ru [81.19.88.5]: 452 4.7.1 Try again later

and

2010-12-07 15:18:09 1PPwTo-0002KU -Kl == [email protected] R=dnslookup T=remote_smtp defer (-46): SMTP error from remote mail server after DATA: host imx2.rambler.ru [81.19.88.5]: 452 4.7.1 Try again later

B what could be the matter? Rambler banned my IP (why then do some emails get through)? Or is it something else?

Answer 1

this is greylisting - a way to combat spam, the server responds to an attempt to send a letter, try again later - at this stage a lot of spam falls off (does not make a second attempt to send), and the correct mail servers must wait and try again. so you need to look at your settings - the server is obliged to resend the letter after such a response, the time is 10-15 minutes.

Answer 2

I think the first thing to do is contact their tech support.
Next - take care of mail server verification (DKIM, for example)

Answer 3

In my server settings, the localhost.localdomain host was registered, because of this, mail.ru did not accept messages. But the MTA was qmail.

Answer 4

I used to use @rambler, often did not receive registration confirmations, etc. Switched to gmail. They had some kind of anti-spam there that was too harsh.
(mail.ru, on the contrary, missed everything and I switched to rambler).

Answer 5

I also use exim4, DKIM, SPF and PTR are configured - no delivery problems have been observed so far.

Answer 6

This is greylisting. It's just that usually spammers don't repeat their emails if they're rejected.
In general, do not touch the queue, it will slowly be sent.

Answer 7

Don't do anything about it. As already mentioned, this is greylisting. Rambler.ru in this sense is the most disgusting.
But you can buy more IPs or rent several VPSs and drive mail through these IPs or intermediate servers.

Answer 8

It looks like the server is being protected from too much soap from your side. Check the IP in the blacklists, set the A and PTR records of the external IP to be mutually inverse, set the spf record. Maybe the suspicions will fall off.