For those who are interested in using a different mobile email strategy, I offer the following. I tested several phones and wasn't too happy with how they handled Zimbra's mobile web client--largely the fault of Verizon and/or the phones, NOT to be blamed on Zimbra!
However, I've just connected an LG enV2 to my Zimbra account and it works quite well. Webmail won't work at all on this phone b/c I've registered my cert with GoDaddy and Verizon doesn't accept their root certs as valid (you can't add root certs-they only accept VeriSign, GTE, Entrust, RSA, & Thawte). But you CAN connect both IMAP and SMTP using their $5/mo email client, and it allows for SSL connections for both IMAP and SMTP so you do not have to go clear-text.
The one wrinkle I've found is that for some reason sent messages don't go to the IMAP "sent" folder; nor have I found a place where they go on the phone either. I worked around this by ticking the "send me a copy" checkbox on the message (which unfortunately can't be set as default), then setting a filter on Zimbra so that if both the "from" and "to" contain my email address, move it to "Sent." This works fine.
I've attached a picture of the email client open to my inbox for anyone who cares. . .