Webmail emails from my domain are blacklisted, how can I fix it?

Question

ubuntu

Good afternoon! I have a problem.. I rented a German server and uploaded my sites there. I created mail for my domain and noticed that letters sent from such an e-mail simply go to spam. Tested on gmail and urk.net.
The content of the letter, albeit for the test, was made complete and normal (subject, body, signature).
How to be? What could be the problem?
Do I need to purchase something, maybe certificates, so that letters do not end up in spam?

Answer 1

As already mentioned in the headlines, you can usually find the reason.
Also, the domain itself (along with the ip address)
can be checked here
lookup.mxtoolbox.com
There may be problems with the settings of your mail server (if everything is set by default). And so he is considered suspicious.

Answer 2

No reasons need to be identified. Set up your account for free on biz.mail.ru
The main thing is that the domain is tied to the machine on which the smtp server is installed.
In the smtp config (I use postfix) specify your domain and that's it... And preferably ssl .