[exim] retry timeout exceeded with greylisting

Hallo,

how can this happen that a message immediatly after "please come back later" gets a timeout as in this case?:

2013-02-21 21:43:28 1U8czG-0000XP-EG <= sender@??? H=autodiscover.tu-berlin.de (exchange.tu-berlin.de) [130.149.7.70] P=esmtps X=TLSv1:AES128-SHA:128 S=4033116 id=77607C03A5F72A479701CC65C73A1DBFCCE0A824@??? T="Stratosphere II Architektur" from <sender@???> for recipient@???
2013-02-21 21:43:48 1U8czG-0000XP-EG SMTP error from remote mail server after RCPT TO:<recipient@???>: host mail.informatik.hu-berlin.de [141.20.20.50]: 451 4.7.1 Greylisting in action, please come back later
2013-02-21 21:44:08 1U8czG-0000XP-EG == recipient@??? R=dnslookup T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<recipient@???>: host mailslv1.informatik.hu-berlin.de [141.20.20.51]: 451 4.7.1 Greylisting in action, please come back later
Feb 21 21:44:08 mailfrontend-3.intern.tu-berlin.de s_local@mailfrontend-3 exim[2585]: [ID 197553 mail.info] 2013-02-21 21:44:08 1U8czG-0000XP-EG ** recipient@???: retry timeout exceeded
2013-02-21 21:44:08 1U8czw-0000kQ-Ff <= <> R=1U8czG-0000XP-EG U=exim P=local S=109116 T="Mail delivery failed: returning message to sender" from <> for sender@???
Feb 21 21:44:08 mailfrontend-3.intern.tu-berlin.de s_local@mailfrontend-3 exim[2585]: [ID 197553 mail.info] 2013-02-21 21:44:08 1U8czG-0000XP-EG Completed QT=42s

Can something against this behaviour be done?


--Frank Elsner