LogFiles - was ist da los?

[dozy]

Hallo Synologiker,

nach gut 3 Wochen problemlosem Betrieb tauchen merkwürdige Dinge in den Logfiles auf:
/opt/var/log/mail.log

Dec 21 02:01:03 Server1 postfix/smtpd[14311]: connect from mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:03 Server1 postfix/smtpd[14313]: connect from mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:03 Server1 postfix/smtpd[14311]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:03 Server1 postfix/smtpd[14313]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:03 Server1 postfix/smtpd[14313]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800
Dec 21 02:01:03 Server1 postfix/smtpd[14311]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800
Dec 21 02:01:04 Server1 postfix/smtpd[14311]: 43D214C0002: client=mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:04 Server1 postfix/smtpd[14313]: 490734C0003: client=mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:04 Server1 postfix/cleanup[14316]: 43D214C0002: message-id=<5F3E651B.9922A67B@rima-tde.net>
Dec 21 02:01:04 Server1 postfix/cleanup[14317]: 490734C0003: message-id=<5F3E651B.9922A67B@rima-tde.net>
Dec 21 02:01:04 Server1 postfix/smtpd[14311]: disconnect from mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:04 Server1 postfix/smtpd[14313]: disconnect from mail.meinprovider24.de[78.46.77.230]
Dec 21 02:01:04 Server1 postfix/qmgr[3746]: 490734C0003: from=<***>, size=2725, nrcpt=1 (queue active)
Dec 21 02:01:04 Server1 postfix/qmgr[3746]: 43D214C0002: from=<***>, size=2568, nrcpt=1 (queue active)
Dec 21 02:01:04 Server1 postfix/local[14318]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:04 Server1 postfix/local[14318]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800
Dec 21 02:01:04 Server1 postfix/local[14318]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:04 Server1 postfix/local[14318]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800
Dec 21 02:01:04 Server1 postfix/local[14319]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:04 Server1 postfix/local[14319]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800
Dec 21 02:01:04 Server1 postfix/local[14319]: user_db_rebuild.c:66 rename(/tmp/.db.user.tmp.name.0959, /tmp/.db.user.name.0959) = (1)/Operation not permitted
Dec 21 02:01:04 Server1 postfix/local[14319]: user_db_check_and_rebuild.c:127 SYNOUserDBRebuild failed, synoerr=0x2800

Kann nicht ganz nachvollziehen was Postfix mit der user_db tut, oder nicht tun kann. Kann mir jemand auf die Sprünge helfen?

Grüsse
Dozy