Not able to send an email because of 553 Relaying disallowed, smtplib python3

Not able to send an email because of 553 Relaying disallowed, smtplib python3

Hello.
I am writting a python3 code for sending emails and unfortunately faced a problem working with zoho mail. Mails from google and other services like yandex (russian company) running like a clockwork.
The error driving me crazy last several hours is:
smtplib.SMTPDataError: (553, b'Relaying disallowed as =?utf-8?q?r=2Ebyku=40genit=2Eorg?=@localhost').
I am not 100 percent sure whether it is a bug with zoho, however all my dreams are about you :) I am new to zoho and  will appreciate any help!
Full program log:
10:32:22.460747 send: 'ehlo [192.168.137.235]\r\n'
10:32:22.483812 reply: b'250-mx.zoho.eu Hello [192.168.137.235] (ns3088370.ip-145-239-232.eu (145.239.232.16))\r\n'
10:32:22.483967 reply: b'250-AUTH LOGIN PLAIN\r\n'
10:32:22.484048 reply: b'250 SIZE 53477376\r\n'
10:32:22.484085 reply: retcode (250); Msg: b'mx.zoho.eu Hello [192.168.137.235] (ns3088370.ip-145-239-232.eu (145.239.232.16))\nAUTH LOGIN PLAIN\nSIZE 53477376'
10:32:22.484737 send: 'AUTH PLAIN AHIuYnlrdUBnZW5pdC5vcmcAZVdrVUNTTlFnaGZm\r\n'
10:32:22.500544 reply: b'235 Authentication Successful\r\n'
10:32:22.500639 reply: retcode (235); Msg: b'Authentication Successful'
10:32:22.502572 send: 'mail FROM:< r.byku@genit.org> size=260\r\n'
10:32:22.513121 reply: b'250 Sender < r.byku@genit.org> OK\r\n'
10:32:22.513407 reply: retcode (250); Msg: b'Sender < r.byku@genit.org> OK'
10:32:22.513773 send: 'rcpt TO:<MAIL @gmail.com>\r\n'
10:32:22.524675 reply: b'250 Recipient <MAIL @gmail.com> OK\r\n'
10:32:22.524935 reply: retcode (250); Msg: b'Recipient <MAIL @gmail.com> OK'
10:32:22.525196 send: 'data\r\n'
10:32:22.536024 reply: b'354 Ok Send data ending with <CRLF>.<CRLF>\r\n'
10:32:22.536258 reply: retcode (354); Msg: b'Ok Send data ending with <CRLF>.<CRLF>'
10:32:22.536477 data: (354, b'Ok Send data ending with <CRLF>.<CRLF>')
10:32:22.537045 send: b'MIME-Version: 1.0\r\nContent-Type: text/plain; charset="utf-8"\r\nContent-Transfer-Encoding: base64\r\nSubject: =?utf-8?q?test1?=\r\nFrom: =?utf-8?q?r=2Ebyku=40genit=2Eorg?=\r\nTo: =?utf-8?q?MAIL=40gmail=2Ecom?=\r\nDate: Sun, 28 Apr 2019 10:32:22 -0000\r\n\r\ndGVzdDI=\r\n.\r\n'
10:32:22.549320 reply: b'553 Relaying disallowed as =?utf-8?q?r=2Ebyku=40genit=2Eorg?=@localhost\r\n'
10:32:22.549414 reply: retcode (553); Msg: b'Relaying disallowed as =?utf-8?q?r=2Ebyku=40genit=2Eorg?=@localhost'
10:32:22.549441 data: (553, b'Relaying disallowed as =?utf-8?q?r=2Ebyku=40genit=2Eorg?=@localhost')
10:32:22.549499 send: 'rset\r\n'
10:32:22.549859 send: 'QUIT\r\n'
Traceback (most recent call last):
  File "./PROGRAM", line 78, in <module>
    main()
  File "./PROGRAM", line 74, in main
    mail.send()
  File "./PROGRAM", line 48, in send
    session.sendmail(self.MAIL_ACCOUNT, self.recipient, message.as_string())
  File "/usr/lib/python3.6/smtplib.py", line 888, in sendmail
    raise SMTPDataError(code, resp)
smtplib.SMTPDataError: (553, b'Relaying disallowed as =?utf-8?q?r=2Ebyku=40genit=2Eorg?=@localhost')