Bulk email, works locally, doesn't work on the server, what's the problem?

Question

Yii

Hello.
--
Those who have worked with swiftMailer know how it works. So, it works for me, and quite quickly, although it sends html letters. Even sends letters to mail.ru
Confirmation e-mails come, as well as to change the password. Runs Yii2 on OpenServer and Server .
You ask, since everything works for you, then why are you writing here? Actually, not everything. There is a script that does mass mailing, through foreach, I did it, as it is written in the documentation,
on OpenServer - it works!
On the server, no.
There are suspicions that there are problems in the mail server, but I don’t understand servers, I know how to operate php.ini
On the other hand, if the problem is in the mail server, why then single letters are sent from the server, and even come to the "inbox" folder on mail.ru?
Naturally: Otherwise, letters would not be sent, but would come to the mail folder, in the form of .eml files. I also looked at the dump, all the data is in place, both the recipient and the sender, and the body of the letter and the subject, everything is in place, there are no errors! I'm shocked! Why the locale can send, and the server - is not present??? I note that the focus did not work only with mass mailing. Everything else is ok, and already running, the longest period of arrival of a letter is 1 second. Please help me figure it out, I really want it to work. )))
'useFileTransport' => false, // на сервере

Answer 1

1. As a rule, local servers do not work with sending, but emulate it, for example, they write to a file. So it's not worth comparing.
2 For mass mailings, there are specialized services with api like:
https://mailchimp.com/
https://www.mailgun.com/
No sane person sends anything from his server in bulk.
3. There are a million places where there may be a problem, identify them without logs, etc. impossible. You wrote a lot of text, useful - 0. Open logs, open debug panel. Give the server configuration, etc.

Answer 2

There are suspicions that the problems are in the mail server, but I don’t understand servers

Well, hire someone who understands. On the server, there can easily be protection against such clever people - no more than N letters in M ​​time. Well, they already said - to do such things from a combat server - just ask for getting into SORBS, SpamHaus, Barracurda and other "black lists" ...