Clearswift MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote attackers to bypass the "text analysis", possibly bypassing SPAM and other filters, by sending an e-mail specifying a non-existent or unrecognized character set.

Clearswift MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote attackers to cause a denial of service via (1) non-ASCII characters in a reverse DNS lookup result from a Received header, which leads to a Receiver service stop, and (2) unspecified vectors involving malformed messages, which causes "unpredictable behavior" that prevents the Security service from processing more messages.

Clearswift MAILsweeper for SMTP before 4.3_13 allows remote attackers to cause a denial of service (infinite loop) via an e-mail with a crafted RAR archive attached.

Clearswift MIMEsweeper 5.0.5, when it has been upgraded from MAILsweeper for SMTP version 4.3 or MAILsweeper Business Suite I or II, allows remote attackers to bypass scanning by including encrypted data in a mail message, which causes the message to be marked as "Clean" instead of "Encrypted".

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use non-standard separator characters, or use standard separators incorrectly, within MIME headers, fields, parameters, or values, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use non-standard but frequently supported Content-Transfer-Encoding values such as (1) uuencode, (2) mac-binhex40, and (3) yenc, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME encapsulation that uses RFC822 comment fields, which may be interpreted as other fields by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use malformed quoting in MIME headers, parameters, and values, including (1) fields that should not be quoted, (2) duplicate quotes, or (3) missing leading or trailing quote characters, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use RFC2231 encoding, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use whitespace in an unusual fashion, which may be interpreted differently by mail clients.