IMAP sensor weird error

Hi there,

We have been configured a lot of IMAP sensors, attacking against a mailbox, and retrieving information about subject, content, etc.

But there's one node where IMAP sensors are reporting a weird messages:

02/01/2014 8:10:11 Backup HBVM DIARI Up 68.949 msec

02/01/2014 8:08:11 Backup HBVM DIARI Down Unexpected: Non-last response line (i.e. a data line) did not start with a *, offending line: Received: from aigu.cat ([192.70.*.]) by correu..com with Microsoft SMTPSVC(6.0.3790.4675);

02/01/2014 8:08:09 Backup HBVM DIARI MSMNT-DN Warning Unexpected: Non-last response line (i.e. a data line) did not start with a *, offending line: Received: from aigu.cat ([192.70.*.]) by correu..com with Microsoft SMTPSVC(6.0.3790.4675);

As you can see, the down status only exists during few seconds, but this status is generating alarms, evidently.

I googled it, but there's no information about this. Any kind of help or idea will be very helpful.

Thanks in advance.

PS: I changed confidential data with *.