Cyrus + LDAP + SASLauth problem. Rewrite login?

[David]

Hello,

I would like to 'rewrite' or associate the user at domain.com mailbox with 
user.domain.com at localhost. 

Due to postfix limitations, it can only accept mail for domain listed in 
mydomains (localhost for example). The problem is adding a domain to 
mydomains list implies a reload of postfix and the decrease of performance, 
besides the procedure is not as simple as creating the accounts in LDAP, I 
need to access to smtp servers.

With a maildrop configuration like user at domain.com -> 
user.domain.com at localhost I would workaround this problem in postfix-side, 
but then I have the problem with the user login of the customers that should 
be user.domain.com (with virtdomains adding @localhost) but should be 
desiderable to use login user at domain.com due to current configuration in 
qmail/qpopper server that we need to integrate.

Thanks in advance, regards
-- 
David