Why do web hosting sites block SMTP?

Question

Email

Many web site hosts prohibit sending mail via smtp, explaining that this is abused and sent spam. And at the same time, they are allowed to send the mail () function through php. Can't send spam through it?

All public mail servers (Yandex, gmail, etc.) already limit the number of emails sent per day. Is there any sense of such a ban on the part of the host?

Answer 1

Mail sent via mail() can be passed through your own spam filter. And through the 25th port, you can connect directly to the recipient's SMTP server and send mail without authorization. From here it is quite a logical conclusion that it is better to cover the 25th port.
If you want to send mail via SMTP with authorization (from your Yandex mailbox), use port 993 and TLS encryption.

Answer 2

For mailings, use services for this purpose, such as https://www.mailgun.com/
, which all large and small mail services know about, and will not shove your letter into spam.
Through smtp they are not allowed because they can be changed like gloves, and as far as I remember, it is impossible to do this through mail ().

Answer 3

The limit on the number of emails sent per hour makes sense, as you can greatly reduce the likelihood of sending spam.
mail() - better to block.
And smtp I don’t see the point, how then to use that mail for normal hosting clients. There are still a lot of people who use smtp to work with mail through Outlook or the like.

Answer 4

through php they can track and restrict and this will require more processor resources, probably
, but in smtp there is less control by the hoster

Answer 5

Of course, it would be justified to save from each hoster