This is how I checked my settings - your's should be similar.
Message>>Tools>>>Options. Tap on your gmail account.
Enter your email address:
johndoe@gmail.com
<next>
Your Name: John Doe
User Name: Jone Doe
Password: type your password
<next>
Account Type: POP3
Name: Gmail
<next>
Incoming mail: pop.gmail.com:995
Outgoing mail: smtp.gmail.com:465
Domain: leave blank
<next>
Options
check - Connect and check for messages every:
15 minutes
<next>
check - Only display messages from the last _ days (put the number of days)
leave blank - Require SSL connection
check - Outgoing mail requires authentication
check - use separate settings
Outgoing settings
User Name: John Doe
Password: enter your password
Domain: leave blank
check - save password
check - require SSL for outgoing mail
(click ok)
<next>
Get message headers only
check - Include
(2) KM message body
click finish
Be sure to logon to your gmail account on your PC and enable POP3 in the settings tab.
With these settings the gmail works great on my Treo, and it also seems to solve the problem of having gmails disappear from the in-box everytime a new sync occurs.
SilkyTofu