Hello everyone, I have four Exchange Server 2010 Sp2 Rollup3, two servers are mailbox and are in DAG, others servers are CAS/HUB. The problem is with OOF, when I send a mail from to a external domain, for example gmail I recieve the return message from OOF, but if I send more messages from the same gmail sender to same internal Exchange recipient, the OOF message is not sent to gmail sender I thinks that Exchange sends only one OOF message per sender. Anyone has already gets this problem?

Hope this URL will help you - http://support.microsoft.com/kb/157961 That is the default behaviour of OOTO and cannot be changed. The only way that you can change is not to use OOTO but use automatic replies, but those have additional risks such as email loops. Thanks