[imp] login information in sent messages

[Jose Marcio Martins da Cruz]

Hello,

I'd like to be able to add a header to all IMP sent messages containing
the login of the one who sent the message. It seems to me that I can
easily use the exemple in the config/header.php file. But how can I get
the login name of the sender ? What's the variable name or function I
can use to do this ?

Thanks

Jose-Marcio