[Exim] Where these messages are going? (Error 501)

Hi!

I'm getting plenty of these errors on my exim:

15093 SMTP<< MAIL FROM:<#@[]>
15093 LOG: smtp_syntax_error MAIN
15093 SMTP syntax error in "MAIL FROM:<#@[]>"
H=gcsnet.prointernet.com.br [200.194.176.70] domain literals not allowed

The question is, what exim does with these messages? they're bounced?

These messages are being forwarded from a qmail machine, like:

postmaster@??? .forwards to central@???

where somedomain.com uses a qmail forward file and otherdomain.com is
the machine that is giving the errors (the log above).

THEN, the emails are staying in the disk on somedomain.com or they're
just lost to the void()? :)

thanks by any help

[]s
core