I did have a small problem receiving mail after my upgrade to 5.0.1

I had to move my postfix virtual.db file from my 4.5.9 backup tree into my zimbra tree.

/opt/zimbra/postfix-2.4.3.3z/conf/virtual.db

postfix/trivial-rewrite[11006]: fatal: open database /opt/zimbra/postfix/conf/virtual.db: No such file or directory

postfix/master[19626]: warning: process /opt/zimbra/postfix-2.4.3.3z/libexec/trivial-rewrite pid 11006 exit status 1

postfix/master[19626]: warning: /opt/zimbra/postfix-2.4.3.3z/libexec/trivial-rewrite: bad command startup -- throttling