==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.9 MYSQL edition.
- Deployed with iRedMail Easy or the downloadable installer? Downloadable Installer
- Linux/BSD distribution name and version: Ubuntu 18.04.2 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I'm not sure exactly what is going on but whenever I send myself a message - from any email account including internal - it does not show up in the inbox on webmail, nor my local computer.
However I have no problem still sending emails, although they can take a couple of minutes to come through, but that isn't entirely unusual.

I've been examining the log files and it almost looks like postfix is deleting the email before dovecot get's a chance to file it in the users folder.

I could be going in totally the wrong direction but I'm at a complete loss.
One error has been corrected, dovecot told me it had stopped supporting pop3s, so gave me the following instructions:
doveconf: Warning: Obsolete setting in /etc/dovecot/dovecot.conf:15: 'pop3s' protocol can no longer be specified (use protocols=pop3). to disable non-ssl pop3, use service pop3-login { inet_listener pop3 { port=0 } }
I have followed these instructions and it hasn't made any difference.

Here is an extract of the log file where mail arrives:

Apr 10 22:17:25 centaur postfix/postscreen[8817]: CONNECT from [209.85.208.51]:39279 to [198.23.199.51]:25
Apr 10 22:17:31 centaur postfix/postscreen[8817]: PASS NEW [209.85.208.51]:39279
Apr 10 22:17:31 centaur postfix/smtpd[8823]: connect from mail-ed1-f51.google.com[209.85.208.51]
Apr 10 22:17:31 centaur postfix/smtpd[8823]: Anonymous TLS connection established from mail-ed1-f51.google.com[209.85.208.51]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
Apr 10 22:17:32 centaur postfix/smtpd[8823]: 44fcSD0K1fz9N3: client=mail-ed1-f51.google.com[209.85.208.51]
Apr 10 22:17:32 centaur postfix/cleanup[8832]: 44fcSD0K1fz9N3: message-id=<CAMgWs=vb6bvXJdwr00gx0BeFO+z6L0tg1Phr7rEhSD39Xu33Og@mail.gmail.com>
Apr 10 22:17:32 centaur postfix/qmgr[5487]: 44fcSD0K1fz9N3: from=<john@*REMOVED*.co.uk>, size=2539, nrcpt=1 (queue active)
Apr 10 22:17:32 centaur postfix/smtpd[8823]: disconnect from mail-ed1-f51.google.com[209.85.208.51] ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
Apr 10 22:17:32 centaur postfix/10025/smtpd[8841]: connect from localhost.localdomain[127.0.0.1]
Apr 10 22:17:32 centaur postfix/10025/smtpd[8841]: 44fcSD56shz9SS: client=localhost.localdomain[127.0.0.1]
Apr 10 22:17:32 centaur postfix/cleanup[8832]: 44fcSD56shz9SS: message-id=<CAMgWs=vb6bvXJdwr00gx0BeFO+z6L0tg1Phr7rEhSD39Xu33Og@mail.gmail.com>
Apr 10 22:17:32 centaur postfix/qmgr[5487]: 44fcSD56shz9SS: from=<john@*REMOVED*.co.uk>, size=3075, nrcpt=1 (queue active)
Apr 10 22:17:32 centaur postfix/10025/smtpd[8841]: disconnect from localhost.localdomain[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Apr 10 22:17:32 centaur amavis[2376]: (02376-01) Passed CLEAN {RelayedInbound}, [209.85.208.51]:39279 [209.85.208.51] <john@*REMOVED*.co.uk> -> <john@*REMOVED*.solutions>, Queue-ID: 44fcSD0K1fz9N3, Message-ID: <CAMgWs=vb6bvXJdwr00gx0B$
Apr 10 22:17:32 centaur postfix/amavis/smtp[8837]: 44fcSD0K1fz9N3: to=<john@*REMOVED*.solutions>, relay=127.0.0.1[127.0.0.1]:10024, delay=0.83, delays=0.22/0.01/0.01/0.59, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:100$
Apr 10 22:17:32 centaur postfix/qmgr[5487]: 44fcSD0K1fz9N3: removed
Apr 10 22:17:32 centaur postfix/pipe[8842]: 44fcSD56shz9SS: to=<john@*REMOVED*.solutions>, relay=dovecot, delay=0.13, delays=0.02/0.01/0/0.09, dsn=2.0.0, status=sent (delivered via dovecot service)
Apr 10 22:17:32 centaur postfix/qmgr[5487]: 44fcSD56shz9SS: removed
Apr 10 22:17:39 centaur postfix/submission/smtpd[8850]: connect from localhost.localdomain[127.0.0.1]
Apr 10 22:17:39 centaur postfix/submission/smtpd[8850]: Anonymous TLS connection established from localhost.localdomain[127.0.0.1]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
Apr 10 22:17:39 centaur postfix/submission/smtpd[8850]: 44fcSM5rwBz9N3: client=localhost.localdomain[127.0.0.1], sasl_method=LOGIN, sasl_username=john@*REMOVED*.solutions
Apr 10 22:17:39 centaur postfix/cleanup[8832]: 44fcSM5rwBz9N3: message-id=<1ba2bb4755b7c56bfa7e080e2027dbb5@*REMOVED*.solutions>
Apr 10 22:17:39 centaur postfix/qmgr[5487]: 44fcSM5rwBz9N3: from=<john@*REMOVED*.solutions>, size=574, nrcpt=1 (queue active)
Apr 10 22:17:39 centaur roundcube: <l1253isp> User john@*REMOVED*.solutions [89.238.150.125]; Message for john@*REMOVED*.solutions; 250: 2.0.0 Ok: queued as 44fcSM5rwBz9N3
Apr 10 22:17:39 centaur postfix/submission/smtpd[8850]: disconnect from localhost.localdomain[127.0.0.1] ehlo=2 starttls=1 auth=1 mail=1 rcpt=1 data=1 quit=1 commands=8
Apr 10 22:17:40 centaur postfix/10025/smtpd[8841]: connect from localhost.localdomain[127.0.0.1]
Apr 10 22:17:40 centaur postfix/10025/smtpd[8841]: 44fcSN1jbNz9Tw: client=localhost.localdomain[127.0.0.1]
Apr 10 22:17:40 centaur postfix/cleanup[8832]: 44fcSN1jbNz9Tw: message-id=<1ba2bb4755b7c56bfa7e080e2027dbb5@*REMOVED*.solutions>
Apr 10 22:17:40 centaur postfix/qmgr[5487]: 44fcSN1jbNz9Tw: from=<john@*REMOVED*.solutions>, size=1948, nrcpt=1 (queue active)
Apr 10 22:17:40 centaur postfix/10025/smtpd[8841]: disconnect from localhost.localdomain[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Apr 10 22:17:40 centaur amavis[2365]: (02365-04) Passed CLEAN {RelayedInternal}, ORIGINATING/MYNETS LOCAL [127.0.0.1]:40008 <john@*REMOVED*.solutions> -> <john@*REMOVED*.solutions>, Queue-ID: 44fcSM5rwBz9N3, Message-ID: <1ba2bb4755b7c$
Apr 10 22:17:40 centaur postfix/amavis/smtp[8837]: 44fcSM5rwBz9N3: to=<john@*REMOVED*.solutions>, relay=127.0.0.1[127.0.0.1]:10026, delay=0.52, delays=0.08/0/0.01/0.43, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025)$
Apr 10 22:17:40 centaur postfix/qmgr[5487]: 44fcSM5rwBz9N3: removed
Apr 10 22:17:40 centaur postfix/pipe[8842]: 44fcSN1jbNz9Tw: to=<john@*REMOVED*.solutions>, relay=dovecot, delay=0.14, delays=0.03/0.02/0/0.1, dsn=2.0.0, status=sent (delivered via dovecot service)
Apr 10 22:17:40 centaur postfix/qmgr[5487]: 44fcSN1jbNz9Tw: removed
Apr 10 22:18:24 centaur postfix/postscreen[8817]: CONNECT from [185.222.209.226]:44584 to [198.23.199.51]:25
Apr 10 22:18:24 centaur postfix/dnsblog[8818]: addr 185.222.209.226 listed by domain zen.spamhaus.org as 127.0.0.4

If anyone can decypher what on earth is going on, I would greatly appreciate it.

I'm happy to post any config files or other logs that are needed, if required.

Many thanks all!
- John