Listnerconfig issues with %

[Rick Williams]

Hi,

Within the Listner config there is a setting for "Reject These Characters in User Names" The default listed characters are %!:@

I am hoping that someone could provide a "technical" or "Security risk" explanation as to why the % sign is blocked.

The company I am working for is part of a large financial organisation. Our head office are (were) sending emails with the % sign as part of the email address. Since the Ironport was implemented it has naturally started to drop the emails.

Any good explanation would greatly assist with avoiding having to remove the % from the Reject list.

Thanks in Advance.

Rick.

[Andreas Mueller · Accepted solution]

Hello Rick,

the characters specified  in that setting (%!:@) are legal per  RFC to be used in usernames, but rarely used today. As for the % symbol,  it is used in some programming languages, such as JavaScript, and also  in SQL as a wildcard character, so my guess is that blocking this  character is supposed to prevent injection of malicious code via the  sender or recipient address to clients that may be vulnerable for this  kind of attacks. This is of cours just an assumption of mine, and not an  official statement, hope it will be helpful, though.

Regards,

Andreas

[Rick Williams]

Hi Andreas,

This was also my thoughts. Unfortunatley without a specific answer I cannot request it be changed.

I will mark your answer as correct, thanks for the response.

Rick.