SMTP content filter engines, including (1) GFI MailSecurity for Exchange/SMTP before 7.2, (2) InterScan VirusWall before 3.52 build 1494, (3) the default configuration of MIMEDefang before 2.21, and possibly other products, do not detect fragmented emails as defined in RFC2046 ("Message Fragmentation and Reassembly") and supported in such products as Outlook Express, which allows remote attackers to bypass content filtering, including virus checking, via fragmented emails of the message/partial content type.

A bug in the HTML parser in a certain Microsoft HTML library, as used in various third party products, may allow remote attackers to cause a denial of service via certain strings, as reported in GFI MailEssentials for Exchange 9 and 10, and GFI MailSecurity for Exchange 8, which causes emails to remain in IIS or Exchange mail queues.

Buffer overflow in the HTTP management interface for GFI MailSecurity 8.1 allows remote attackers to execute arbitrary code via long headers such as (1) Host and (2) Accept in HTTP requests. NOTE: the vendor suggests that this issues is "in an underlying Microsoft technology" which, if true, could mean that the overflow affects other products as well.