This thread looks to be a bit dated, but I hope this helps:
To submit false positives for McAfee GW edition you can use the following steps, which can be found in KB62662:
* McAfee Gateway Anti-Malware (Secure Anti Malware) via email:
1. Place the submission in a password-protected ZIP file, using the word "infected" as the password (without quotes).
2. Email the submission to email@example.com
3. If you believe the submission is a false detection, put "Possible False" in the subject line of the email.
4. After received, the sample will be validated for detection issues and whether it is a known clean file, a possible false detection, or a completely unknown file. A Sample that is a possible false detection or unknown file will be escalated for review and further processing.
5. Once a submission status is confirmed, an email update will be sent to the submitter.