[Exim] Just Only Holding Mails

    We are using sendmail for ETRN support. Maybe everbody know, when
first mail server goes down or connection problem then second mail server (
I'mean ETRN Server ) holding mails after first server up , it's sending ETRN
command and takes emails from ETRN Server.

    Problem is, I have to add domain name to relay list for holding mail
when first mail server goes down. At this moment anybody can send a mail
with using this domain name on From prompt ..

    Does it possible to only hold mails for some domain? But nobody can
sent a mail with using those domains names .. Does it possible ....