How to configure postfix so that emails do not end up in the SPAM folder in gmail.com?

Question

Mail server

How to configure postfix so that emails do not end up in the SPAM folder in gmail.com?
The situation is this. Emails sent from postfix end up in the SPAM folder on gmail. On mail and other services, everything seems to be normal. What needs to be corrected or in what direction to move? Found a mismatch error between the domain ip and the bind ip. Corrected, now the bind-ip matches the ip-domain, but this does not solve the situation. What do you advise?

Answer 1

Adjust SPF, DKIM and DMARK. Get yourself a gmail account, send an email to it. If it got into spam - look at the reasons.
If you send out a large volume of letters to gmail (hundreds per week), then register your domain on postmaster.gmail.com and check the statistics after a while.
Well, do not send letters that users will mark as spam - each such letter reduces the credibility of the sender and increases the likelihood of future letters falling into spam.