What is a simple and free smtp service for a site so that spf and dkim look correct?

Question

Mail server

Hello.
I'm already tired of fiddling with the settings of mail servers - I want to try using external smtp
Please advise something that will send letters with DKIM, etc. look correct.
Well, in the same place you understand what the essence is - the letter has one domain with the return address, but in fact it is sent from another, in general, all this dregs and the letter is sent to the spam folder, but you don’t want to.
The functions are standard for the site: user notifications, etc.
What do you personally use?
Thank you.

Answer 1

Yandex mail is free and allows you to configure DKIM SPF and everything you need

Answer 2

Own mailer