Undelivered Mail Returned to Sender

[Mail Delivery System]

This is the mail system at host bizcloud-send.kinexbearings.sk.

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

<cygwin@cygwin.com>: host sourceware.org[8.43.85.97] said: 550 5.7.1 Blocked by
    SpamAssassin (in reply to end of DATA command)