Delivering to user@domain versus user@host.domain

[Don Doumakes]

I'm a cyrus-imap newbie, setting up a replacement mail server with 
Cyrus.  I've got it close to exactly how I want it, and could use some 
help taking the next step.

I'm running cyrus-imapd 2.2.0 alpha, compiled from source, and 
cyrus-sasl 2.1.10-1, installed from RPM.  The /etc/imapd.conf file is:

#==============================
configdirectory: /var/imap
defaultpartition: two
partition-two: /usr2
partition-three: /usr3
partition-four: /usr4
partition-five: /usr5
partition-six: /usr6
partition-seven: /usr7
partition-eight: /usr8
partition-nine: /usr9
hashimapspool: yes
admins: cyrus at donner.cannibals.org
allowplaintext: yes
loginrealms: donner.cannibals.org
sasl_pwcheck_method: auxprop
sasl_mech_list: PLAIN
unix_group_enable: no
#defaultdomain: donner.cannibals.org
servername: donner.cannibals.org
virtdomains: yes
singleinstancestore: yes
#Necessary?
#sasl_sasldb_path: /etc/sasldb2
#==============================

With this configuration, I'm able to create a mailbox named 
user.don at donner.cannibals.org.  I can log in to that account, and 
deliver to the mailbox.

I then modify /etc/imapd.conf so the "admins" and "loginrealms" entries 
are no longer donner.cannibals.org but rather cannibals.org.  (Of 
course I clean up from the first experiment, restart imapd and all 
that.)

Now I can create a mailbox named user.don at cannibals.org.  I can log in, 
but if I attempt to deliver mail to don at cannibals.org I get a "User 
unknown" error.

I would be grateful for a hint.

-- 
Don Doumakes