Why is Exim not sending emails?

Question

Layout

There is a relay, everything worked fine, since some day letters have been stuck in the queue and only from subdomains (which go through the relay)
MX - the norms have not changed
Cause output:
[[email protected] ~]# exim -Mvl 1iPl2s-0008HK-R2
2019-10-30 13:17:43 Received from <> R=1iPl2r-0008HF-Mx U=exim P=local S=9308
2019-10-30 13:17:43 H=post.in-b-ox. en [78.108.90.159] SMTP error from remote mail server after RCPT TO:: 550 relay not permitted
2019-10-30 13:17:43 [email protected] R=dnslookup T=remote_smtp H= post.in-b-ox.ru [78.108.90.159] X=TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no: SMTP error from remote mail server after RCPT TO:: 550 relay not permitted
*** Frozen (delivery error message)
what could break?
ps was hacked (of another system) and spam with the signatures of these domains and others has passed a little, others are now sending (repaired) but these are not, while the letter reaches Yandex, only to the mail

Answer 1

Dig towards the parallax effect.

Answer 2

if in detail, then there are several pictures ... they are in png, i.e. transparent and each of them shows triangles, squares, etc.
the principle of operation is shown in this example, i.e. we shift the layers one by one when moving the mouse

Answer 3

If you want the figures to move at different speeds, look in the direction of parallax. If you need an easy way, you can bind the background position to the mousemove event.
Example: https://codepen.io/skyajay/pen/rVVPdX

Answer 4

It is worth checking the SPF record in DNS.