если правильно понял то вот.
2 12:49:00 d-hc postfix/smtpd[9680]: warning: ppp109-252-135-232.pppoe.spdop.ru[109.252.135.232]: SASL CRAM-MD5 authentication failed: Connection lost to authentication server
Feb 2 12:49:00 d-hc postfix/smtpd[9680]: 661904A043FF: client=ppp109-252-135-232.pppoe.spdop.ru[109.252.135.232], sasl_method=CRAM-MD5, sasl_username=admin@.ru
Feb 2 12:49:00 d-hc postfix/cleanup[9607]: 661904A043FF: message-id=<AD21CEB7-C151-4552-8761-155EC4647156@.ru>
Feb 2 12:49:00 d-hc postfix/qmgr[26153]: 661904A043FF: from=<admin@.ru>, size=669, nrcpt=1 (queue active)
Feb 2 12:49:00 d-hc postfix/pipe[9613]: 661904A043FF: to=<admin@.ru>, relay=dovecot, delay=0.23, delays=0.17/0/0/0.05, dsn=4.3.0, status=deferred (temporary failure)