Recommend a company/service offering a highly reliable mail server for your domain?

Question

Mail server

Recommend a company/service offering a highly reliable mail server for your domain?
I am interested in the availability of a guaranteed SLA, the possibility of having an office or representative office in St. Petersburg, where one could call / talk to live employees / drive up to get some kind of document in case there was a technical failure and for some time the mail server did not work for submission to state bodies of the Russian Federation. About the last point, there may be a bust, but the point is that it is desirable to have a representative office or office in St. Petersburg, and the opportunity to talk live with them, contact them, and not write a letter to the support somewhere.
Only companies that store data in the Russian Federation.
And yet, in order to have a reasonable limit on the number of simultaneous connections, nic.ru mail servers have 7 simultaneous connections to mail at the same time, and we have about 20 computers, 20 employees simultaneously working with mail.
Mail for business Mail.ru paid tariff starts from 2000 rubles per month, it’s somehow expensive, Yandex mail doesn’t say anything about SLA at all, and it’s also not clear there is any opportunity to talk to live employees in case something happens

Answer 1

You have too big a fork between requirements and budget. Those who need an SLA, a personal manager and all that, usually do not bother with the question "how much does it cost" - because at some level the price ceases to matter at all. Those who count money usually don't bother with SLAs.
Hire an admin and install your mailer. If you don't get in, then at least you will understand what they charge money for :)

Answer 2

for some time the mail server did not work for submission to the state bodies of the Russian Federation

And where is the guarantee that your state recipient had a working mail server.
In the Russian Federation, although the courts accept e-mails as evidence, the concept of "guaranteed delivery by e-mail" is absent as a class.
Any smaller and cheaper desk will not be able to guarantee you stability. She just doesn't have the resources.
The post office is no longer a business. Nobody needs this, since there are free monsters GMail, Mail.ru, etc.

Answer 3

And yet, in order to have a reasonable limit on the number of simultaneous connections, nic.ru mail servers have 7 simultaneous connections to mail at the same time, and we have about 20 computers, 20 employees simultaneously working with mail.

Well, get a separate mailbox for each employee. And make the incoming address a mailing list for all employees.