nbsmtp/problem with sender field

[Olivier Regnier]

Hello,

I written a script with an function to send reports by email.

Here is my function:
sendmail() {
        date=`date +%d/%m/%Y`
        time=`date +%H:%M:%S`
        mail -s "[FreeBSD/Ports-tree]-Update"-"($date/$time)" \
        me at domain.org <$logfile
}

Here is my .mailrc file:
set sendmail="/root/scripts/nbsmtp.sh

and my nbsmtp.sh script:
#!/bin/sh
/usr/local/bin/nbsmtp -h ssl0.ovh.net -f me at domain.org -d mydomain -p 
465 -U admin at mydomain -P password -M l -s -V

then, that work very well but when i recieved an email the sender field  
=  anonymous at mx1.ovh.net

I don't understand what happened because i use correctly the -f option. 
Can you help me please ?

Thank you :)