How to check email?

Question

Email

Recently, the company switched to Mail.ru e-mail for business, and some employees began to complain that their letters did not reach the recipient (the letter was sent in the mail, and when you call the person to whom the letter was sent, they say they don’t see it), they also say that sometimes letters do not reach them.
I myself have not encountered such a problem, and people who send / receive (to us / from us) mail are often not very familiar with the computer to conduct joint tests with them, how can I test this problem to first make sure whether it really exists ?
If there is a problem, then how to find out on whose side it is (our mail.ru or the recipient)?
Have you had similar cases and what is the easiest way to deal with them without changing the mail service?

Answer 1

Basically, it will not work to test letters, you will have to write to those support.
You can test whether mail.ru gives the correct settings (and not only it) using these tools:
www.mail-tester.com
www.kitterman.com/spf/validate.html
mxtoolbox.com
www.senderbase.org
etc.

Answer 2

Sorry for the banality, but the spam folder was checked by the recipients?

Answer 3

Hello,
send me a PM with information about the domain and undelivered letters (from what address, to what and when).