Undelivered Mail Returned to Sender

[Mail Delivery System]

This is the mail system at host mx02.pronto.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.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<kate260199 at irr.ru>: host exchedge.pmh.int[10.77.57.18] said: 550 5.1.1 User
    unknown (in reply to RCPT TO command)
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From: <security at pidgin.im>
Subject: *****SPAM***** In my life there is no happiness, I want to find it!
Date: 16 May 2018 21:02:14 +0300
Size: 2554
URL: <https://pidgin.im/cgi-bin/mailman/private/security/attachments/20180516/eeae06ff/attachment.mht>