Incoming, outgoing mail on different servers?

Question

Mail server

Hello
I'm setting up VDS KVM (so far 1Gb RAM, 1 core, most likely it will be 2Gb, 2 cores).
You will need mailboxes from some of them will be mailed (not thousands and millions, but hundreds in a short period of time) using specialized software.
The idea is this: connect corporate mail (mail, Yandex or gmail) to incoming mail in order not to overload the server on which the site is located, not to fight spam, incoming viruses, not to overflow (and not to monitor its overflow), not to lose letters. And outgoing send your server . I read that (mail, yandex, gmail) will not allow you to engage in such mailings and trust more domains, of course with some weight, otherwise spam.
Is it worth the bother? Which scheme is simpler and viable in your opinion for the task at hand?
If so, what records should be made in DNS?

Answer 1

The scheme has the right to life. For correct mailings, do the following:

• It is mandatory to specify the reverse zone in the provider's dns
  
• In your dns (will you have yandex dns?) you need to make a txt entry with the correct sfp and ip of your server
  
• The server hello string must match the name in the reverse zone
  
• The presence of dkim and dmarc is highly welcome
  
• Carefully configure the rights to send mail. How do you plan to authorize senders?
  

Answer 2

I will either order my DNS on which the server is located, or I will order it as a separate service (I expect that the response will be faster, because the server is in Moscow, the consumers are in the Siberian Federal District).
Authorization of senders by what the ISP manager offers.
Thanks for the answer.
PS I set up mail once and for a very long time. Then I did not bother, everything worked. Now the task has become more difficult.