[exim] Question about Exim

Hello Exim users,

I want based on the SMTP authenticated use, that specifies what domains
a user may use after the at!

I mean, I am Customer1 and my email address is: info@???, this
is the only domain that it's allowed to use as a sender address

And Customer2 had domain: customera.com and customerb.com, he may send
email with either of them?

And myself the system administrator don't have any restrictions, or
maybe for safety that I can secure it for only the domain that I want,
to use otherwise being an open relay / SPAM problem's!?

Thanks,

Marco de Roo
MDR Support - the Netherlands