Question

Не отправяются письма, выдает ошибку 

This is the mail system at host yandex.ru.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

You can find the the possible reasons of the undelivered message letter here:
https://yandex.com/support/mail-new/wizard/zout_send/not-got-report-yes-other.html

Please, do not reply to this message.


<marketing1@technodom.com>: host xmail.technodom.com[46.229.140.95] said: 554
    5.7.1 <m.sherbakov@vershina.ml>: Sender address rejected: # DOMAIN .ml (in
    reply to RCPT TO command)

Статус доставки:

Reporting-MTA: dns; forward500p.mail.yandex.net
X-Yandex-Queue-ID: 0DCE594023E
X-Yandex-Sender: rfc822; m.sherbakov@vershina.ml
Arrival-Date: Wed, 30 Jan 2019 14:20:04 +0300 (MSK)

Final-Recipient: rfc822; marketing1@technodom.com
Original-Recipient: rfc822;marketing1@technodom.com
Action: failed
Status: 5.7.1
Remote-MTA: dns; xmail.technodom.com
Diagnostic-Code: smtp; 554 5.7.1 <m.sherbakov@vershina.ml>: Sender address
    rejected: # DOMAIN .ml

Answer 1

Пишите в техподдержку яндекс почты https://yandex.ru/support/mail/bounces/other.html внизу жмите на кнопку Написать в службу поддержки, в описании приведите текст ошибки и ожидайте ответа.