Intrusion Prevention

IMAP.Unknown.Reply

Description

This signature indicates detection of a SMTP protocol anomaly of which an unknown response from a server is sent.

Affected Products

Any host running SMTP services

Impact

Protocol Anomaly: This is an anomaly which may also indicate attack attempts in some cases.

Recommended Actions

This indicates detection of traffic that does not comply with the protocol standard.
Monitor the traffic from that network for any suspicious activity.