Do Yandex.Mail and Gmail check ptr records when they receive emails?

Question

Domain Name System

Good afternoon.
I ran into this problem: when sending a letter to a mail located on siol.net, exchange returns the following:
mailhub.siol.net #554 5.7.1 : Recipient address rejected: Blocked - Your IP [our_ip] has no corresponding reverse (PTR) address. Ask your Internet Service Provider to assign you IP with valid reverse (PTR) record. ##
However, nslookup and all Internet services indicate that the PTR record is quite correct and it seems to me that the dns server of the siol.net server itself is messed up. Well, actually the question is: Yandex mail and gmail check the validity of the ptr record?
ps The mail server is its own (exchange 2007), DNS is also its own, it's all in America. The validity of the PTR was tested on several different internet services and nslookup.

Answer 1

Gmail and Yandex check PTR, but this is not their only sign of spam.
They will not refuse to accept the letter, but first they will throw it in the Spam folder.
Write to siol.net admins.
If it's their fault, then let them fix it.