critical applications

Dear friends,

i am planning to use openldap 2.4.26 and bdb 4.6.21v0 for mission critical application mailing system. I tried some time ago i tried to implement a mail server using qmail, qmail-ldap patch, openldap and bdb but while time passed and email were coming and going, slapd was eating all system memory and needed to be restart. I wonder if someone in the mailing list have used such technologies so far and with which degree of success ?

Thanks in advance for your time and cooperation.

Best regards.

[]s gustavo.