Pro tento účel je možno použít kombinaci programů Qmail a vchkpw

Apt-get install qmail-src ucspi-tcp-src vchkpw
Build-qmail
Build ucspi-tcp

S programem qmail je možno použít vlastní skript pro kontrolu hesla checkpasswd.

Další možností je pro POP/IMAP použít courier-pop a courier-imap

V sendmailu je to možno udělat takto:

for virtual domains pop/imap servers... 

/etc/mail/local-host-names ( sendmail.cw )
        domain_1.com
        pop.domain_1.com
        mail.domain_1.com

        domain_two.com
        pop.domain_two.com
        mail.domain-two.com

        # this is the "real" machine name       
        primary.com
        pop.primary.com
        mail.primary.com

pinging those domain names should have the same ip# if oyu wnat
to use just one server... ( fix your dns till it works right )

/etc/mail/virtusertable
        webmaster@domain_1.com  webmaster,webmaster_1@yahoo.com
        webmaster@domain_two.com  webmaster,webmaster_two@excite.com
        webmaster@primary.com   webmaster

who can send email thru your server
 ( arriving at the recepeint as coming from somebody@domain_1.com

        /etc/mail/relay-domains
        /etc/mail/relay_allow

if you wanna stop some spam... ( the hard way )
        /etc/mail/access
-->>
-->> make the new db in /etc/mail && dont forget to restart sendmail
-->>

now setting up pop/imap.... ( use secure pop3s or imaps instead )
        ..
        standard issue...
        ...
        /etc/hosts.allow
        /etc/hosts.deny
        ..

test it
        telnet pop.domain_1.com 110  ( regular pop )
        telnet pop.domain_1.com 995  ( might fail - checks protocol )

        - use a SSL enable client to do secure pop3/secure imaps
                IE, netscape, eudora, etc..etc..
                stunnel, ssh, etc...


Secure pop3 ( howto info )

        http://www.Linux-Sec.net/Mail/secure_pop3.txt