Edit /etc/sendmail.cf

Rule set 93 & 94 (masquerade)

Replace $j (host.domain) by $m (domain)

!!!Here under are these 2 Rule sets, I putted the modification between
double-quote("$m"). Don't put these double-quote but rather what they
contain!!!
################################################## #################
### Ruleset 93 -- convert header names to masqueraded form ###
################################################## #################

S93

# handle generics database
#R$+ < @ $=G . > $: < $1@$2 > $1 < @ $2 . > @ mark
#R$+ < @ *LOCAL* > $: < $1@$j > $1 < @ *LOCAL* > @ mark
#R< $+ > $+ < $* > @ $: < $(generics $1 $: $) > $2 < $3 >
#R< > $+ < @ $+ > $: < $(generics $1 $: $) > $1 < @ $2 >
#R< $* @ $* > $* < $* > $@ $>3 $1 @ $2 found qualified
#R< $+ > $* < $* > $: $>3 $1 @ *LOCAL* found
unqualified
#R< > $* $: $1 not
found

# special case the users that should be exposed
R$=E < @ *LOCAL* > $@ $1 < @ "$m" . > leave exposed
R$=E < @ $=M . > $@ $1 < @ $2 . >
R$=E < @ $=w . > $@ $1 < @ $2 . >

# handle domain-specific masquerading
R$* < @ $=M . > $* $: $1 < @ $2 . @ $M > $3 convert
masqueraded doms
R$* < @ $=w . > $* $: $1 < @ $2 . @ $M > $3
R$* < @ *LOCAL* > $* $: $1 < @ "$m" . @ $M > $2
R$* < @ $+ @ > $* $: $1 < @ $2 > $3 $M is null
R$* < @ $+ @ $+ > $* $: $1 < @ $3 . > $4 $M is not null


################################################## #################
### Ruleset 94 -- convert envelope names to masqueraded form ###
################################################## #################

S94
R$* < @ *LOCAL* > $* $: $1 < @ "$m" . > $2


compile sendmail.cf by the command: sendmail -bi

refresh -s sendmail

Hope this .