Recipient address rejected: Service is unavailable (try later)

[KatyComputer]

We are seeing quite a few "Recipient address rejected: Service is unavailable (try later)" messages in mail.log.

The email will be accepted at 8:47, rejected at 8:51, then accepted again at 9am

Any ideas what's going on? Yesterday, I deleted /var/lib/postfix/verify_cache.db, it doesn't seem probable that it's corrupted again. We are seeing it when the destination host is Office 365 and when destination host is cPanel (Exim/Dovecot).

Oct 18 08:44:43 stl-mx pmg-smtp-filter[8060]: 1FBCF5DA9C1C81C7F5: accept mail to <a@h.com> (D17D71FBDE) (rule: default-accept)
Oct 18 08:44:43 stl-mx postfix/lmtp[8134]: F36231FBCE: to=<a@h.com>, relay=127.0.0.1[127.0.0.1]:10024, delay=4.6, delays=0.76/0/0.04/3.8, dsn=2.5.0, status=sent (250 2.5.0 OK (1FBCF5DA9C1C81C7F5))
Oct 18 08:44:43 stl-mx postfix/smtp[6833]: D17D71FBDE: to=<a@h.com>, relay=cp.fastnet1.com[68.187.12.72]:8888, delay=0.13, delays=0.05/0/0.07/0.01, dsn=2.0.0, status=sent (250 OK id=1iLSYd-00030c-VY)
Oct 18 08:47:40 stl-mx pmg-smtp-filter[8135]: 1FD5C5DA9C27BD2225: accept mail to <a@h.com> (726CB1FDE3) (rule: default-accept)
Oct 18 08:47:40 stl-mx postfix/lmtp[7686]: B59811FDDA: to=<a@h.com>, relay=127.0.0.1[127.0.0.1]:10024, delay=0.89, delays=0.19/0/0.04/0.66, dsn=2.5.0, status=sent (250 2.5.0 OK (1FD5C5DA9C27BD2225))
Oct 18 08:47:40 stl-mx postfix/smtp[6833]: 726CB1FDE3: to=<a@h.com>, relay=cp.fastnet1.com[68.187.12.72]:8888, delay=0.12, delays=0.05/0/0.06/0.01, dsn=2.0.0, status=sent (250 OK id=1iLSbU-0003bn-Id)
Oct 18 08:51:58 stl-mx postfix/smtpd[7741]: NOQUEUE: reject: RCPT from warrentonoil.pdi-cloud.com[64.9.152.145]: 450 4.7.1 <a@h.com>: Recipient address rejected: Service is unavailable (try later); from=<d@w.com> to=<a@h.com> proto=ESMTP helo=<c2011-02.c2011.local>
Oct 18 08:52:57 stl-mx postfix/smtpd[7221]: NOQUEUE: reject: RCPT from warrentonoil.pdi-cloud.com[64.9.152.145]: 450 4.7.1 <a@h.com>: Recipient address rejected: Service is unavailable (try later); from=<d@w.com> to=<a@h.com> proto=ESMTP helo=<c2011-02.c2011.local>
Oct 18 08:53:58 stl-mx postfix/smtpd[7332]: NOQUEUE: reject: RCPT from warrentonoil.pdi-cloud.com[64.9.152.145]: 450 4.7.1 <a@h.com>: Recipient address rejected: Service is unavailable (try later); from=<d@w.com> to=<a@h.com> proto=ESMTP helo=<c2011-02.c2011.local>
Oct 18 09:00:59 stl-mx pmg-smtp-filter[8689]: 20AA95DA9C599ED7BF: accept mail to <a@h.com> (B707B20ABF) (rule: default-accept)
Oct 18 09:00:59 stl-mx postfix/lmtp[7686]: CB0C320AA8: to=<a@h.com>, relay=127.0.0.1[127.0.0.1]:10024, delay=2, delays=0.15/0/0.04/1.8, dsn=2.5.0, status=sent (250 2.5.0 OK (20AA95DA9C599ED7BF))
Oct 18 09:00:59 stl-mx postfix/smtp[8619]: B707B20ABF: to=<a@h.com>, relay=cp.fastnet1.com[68.187.12.72]:8888, delay=0.15, delays=0.04/0/0.09/0.01, dsn=2.0.0, status=sent (250 OK id=1iLSoN-0005JF-SV)

 

[Stoiko Ivanov]

hmm - please post more complete logs of those messages (seems there should be some messages before).

* do you have greylisting enabled in PMG?
* also could it be that cp.fastnet1.com replies with 450 - what do the logs of that server say?

I hope this helps!