Cpanel email spammed?

Before 4 months a problem has occurred to my hosted email.

My clients were trying to send me an email to my hosted email (info@mydomain.com) and always were getting an error like this bellow although I received the email.

My web hosting provider assured me that nothing happened to my cpanel package. I have some other packages in this same server and everything is working perfect.

My clients keep complaining that they receive this error when trying to send me an email although I get the emails.

In addition to this problem, a lot of spam emails delivered to my inbox every day.

I hired someone to fix my spf and dkim but nothing has changed.

Have you any idea what happened?

Mail delivery failed: returning message to sender  This message was created automatically by mail delivery software.  A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:   securedserver001@mail.ua    (generated from info@mydomain.com)    host mxs.mail.ru [94.100.180.104]    SMTP error from remote mail server after end of data:    550 spam message rejected. Please visit http://help.mail.ru/notspam-support/id?c=MkQzjxr5SQM7sHtw55eQjviDdemyJDJvXsDGek9T2L5laB_SrV4UohQAAABPIAEAQNHiCw~~ or  report details to abuse@corp.mail.ru. Error code:    8F3344320349F91A707BB03B8E9097E7E97583F86F3224B27AC6C05EBED8534FD21F6865A2145EAD. ID:    000000140001204F0BE2D140.