sending mail from non-existant mailbox is possible ?

[fgilain]

Hi all,

i juste have received an email from a partner's web application.
my problem is that this is mail has the following settings :

my server, let's say smtp.company.com, is hosting the domain company.com.

my partner has built a web application that is sending email to one of my existing mailboxes using a non existing one :

existing one : user1@company.com

sender used by web application : user_unknown@company.com

why does my plesk 7.5 server accepts this email from a non-existing email account (or alias) just because he is using @company.com domain for its bad email ? how can i prevent it ?

thanks

Florent

 

[fgilain]

any idea ?