@www.localdomain noreply@preferans.de

smtp_generic_maps = hash:/etc/postfix/generic

From: noreply@preferans.de     <--- non-existing address at my domain
Reply-To: First.Last@gmail.com <--- my private mail address

Aug 16 18:20:44 www postfix/master[1006]: daemon started -- version 2.10.1, configuration /etc/postfix
Aug 16 22:29:20 pref postfix/cleanup[9031]: 785952C03A8: message-id=<20170816202920.785952C03A8@pref.localdomain>
Aug 16 22:29:20 pref postfix/bounce[9033]: 5B56F2C03A7: sender non-delivery notification: 785952C03A8
Aug 16 22:29:20 pref postfix/qmgr[24449]: 785952C03A8: from=<>, size=3262, nrcpt=1 (queue active)
Aug 16 22:29:20 pref postfix/qmgr[24449]: 5B56F2C03A7: removed
Aug 16 22:29:22 pref postfix/smtp[9009]: connect to preferans.de[88.99.244.39]:25: Connection refused
Aug 16 22:29:22 pref postfix/smtp[9009]: 785952C03A8: to=<noreply@preferans.de>, relay=none, delay=1.5, delays=0/0/1.5/0, dsn=4.4.1, status=deferred (connect to preferans.de[88.99.244.39]:25: Connection refused)
Aug 16 22:38:51 pref postfix/qmgr[24449]: 785952C03A8: from=<>, size=3262, nrcpt=1 (queue active)
Aug 16 22:38:51 pref postfix/smtp[9208]: connect to preferans.de[88.99.244.39]:25: Connection refused
Aug 16 22:38:51 www postfix/smtp[9208]: 785952C03A8: to=<noreply@preferans.de>, relay=none, delay=571, delays=571/0.01/0.01/0, dsn=4.4.1, status=deferred (connect to preferans.de[88.99.244.39]:25: Connection refused)
Aug 16 22:48:51 www postfix/qmgr[24449]: 785952C03A8: from=<>, size=3262, nrcpt=1 (queue active)
Aug 16 22:48:51 www postfix/smtp[9393]: connect to preferans.de[88.99.244.39]:25: Connection refused
Aug 16 22:48:51 www postfix/smtp[9393]: 785952C03A8: to=<noreply@preferans.de>, relay=none, delay=1171, delays=1171/0.01/0.01/0, dsn=4.4.1, status=deferred (connect to preferans.de[88.99.244.39]:25: Connection refused)
Aug 16 23:08:51 www postfix/qmgr[24449]: CF37F2C039F: from=<noreply@preferans.de>, size=1234, nrcpt=1 (queue active)
Aug 16 23:08:51 www postfix/qmgr[24449]: 785952C03A8: from=<>, size=3262, nrcpt=1 (queue active)
Aug 16 23:08:51 www postfix/smtp[9797]: connect to preferans.de[88.99.244.39]:25: Connection refused
Aug 16 23:08:51 www postfix/smtp[9797]: 785952C03A8: to=<noreply@preferans.de>, relay=none, delay=2371, delays=2371/0.01/0.01/0, dsn=4.4.1, status=deferred (connect to preferans.de[88.99.244.39]:25: Connection refused)
Aug 16 23:08:51 www postfix/smtp[9796]: connect to gamai.com[67.227.226.241]:25: Connection refused
Aug 16 23:08:51 www postfix/smtp[9796]: CF37F2C039F: to=<vs20132013@gamai.com>, relay=none, delay=4588, delays=4588/0.01/0.13/0, dsn=4.4.1, status=deferred (connect to gamai.com[67.227.226.241]:25: Connection refused)
Aug 16 23:48:52 www postfix/qmgr[24449]: 785952C03A8: from=<>, size=3262, nrcpt=1 (queue active)
Aug 16 23:48:52 www postfix/smtp[10420]: connect to preferans.de[88.99.244.39]:25: Connection refused
Aug 16 23:48:52 www postfix/smtp[10420]: 785952C03A8: to=<noreply@preferans.de>, relay=none, delay=4772, delays=4772/0.01/0.01/0, dsn=4.4.1, status=deferred (connect to preferans.de[88.99.244.39]:25: Connection refused)

# sudo mailq
-Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient-------
CF37F2C039F     1234 Wed Aug 16 21:52:22  noreply@preferans.de
                 (connect to gamai.com[67.227.226.241]:25: Connection refused)
                                         vs20132013@gamai.com

785952C03A8     3262 Wed Aug 16 22:29:20  MAILER-DAEMON
                (connect to preferans.de[88.99.244.39]:25: Connection refused)
                                         noreply@preferans.de

BD4222C03B6     1219 Thu Aug 17 07:48:48  noreply@preferans.de
(host mx.yandex.ru[87.250.250.89] said: 451 4.5.1 The recipient <ebotstoreru@yandex.com> has exceeded their message rate limit. Try again later. 1502957639-8f63s3727h-Dw8G1QLj (in reply to end of DATA command))
                                         ebotstoreru@yandex.com

-- 6 Kbytes in 3 Requests.