What causes an SMTP error?

Question

Exim

Good afternoon, can someone explain to a non-knowledgeable person what is happening here without sending to Google))?

2020-01-24 09:06:10 1iub3z-00033F-3B SMTP error from remote mail server after MAIL FROM:<[email protected]> SIZE=2785: 421 4.7.0 [TSS04] Messages from 109.235.246.82 temporarily deferred due to user complaints - 4.16.55.1; see https://help.yahoo.com/kb/postmaster/SLN3434.html

Answer 1

Here, right in the log, a page with information about the error is given:
https://help.yahoo.com/kb/postmaster/SLN3434.html
Your SMTP IP address has been banned by the recipient's server. The filter is temporary, usually for 4 hours. If you are a mail server admin and the error persists after 48 hours, please contact Yahoo.