[HD2 Windows Mobile 6.5 Q&A, Help & Troubleshooting] Snarksneeze:
Google Sync is a free service that allows you to sync your contacts, email and calendar with your gmail account.

It is a two-way sync, meaning that if you add an appointment or contact to your phone, it will upload to Google's cloud and update your gmail information as well.

I use Google Sync to keep my contacts in the cloud, vs using myPhone since I have multiple phones but only one Windows Live account. If you have ever synced two phones to myPhone under one account, you'll see right away why this is a bad thing.

One of my favorite benefits from using Google Sync is the fact that it not only stores my phone contacts, it also stores their facebook links and contact pictures as well. This means that I can freely flash another ROM without worrying about backing up all of my contacts to SIM or myPhone and then manually updating all of the information for them.

The best part of Google Sync has to be the push email service. As emails arrive (assuming you have set the account up correctly), they will be pushed to your phone via ActiveSync. You don't have to be at your computer for this, it's done over the air.

The only think Google Sync can't do is sync Tasks. If you choose Tasks during the setup, you will receive a cryptic error.

Now that I've told you about the benefits of Google Sync, let's go over how to use it. This assumes you have an existing gmail account. I don't know how to sync with Google without a gmail account, sorry.

I always add my hotmail account first. For some strange reason you can never go back and edit the settings for the first mail account you setup on Windows Mobile, so I use my hotmail account for this.

Steps:

Select your Mail tab and hit the Menu button

Choose "Add Account"

Under "Choose a Mail Provider", select "Outlook" (Don't select Gmail!)

Put your entire gmail address (you@gmail.com) in the "Email address" box, followed by your password.

Select "Next"

Under "User name" put your email address (you@gmail.com) again.

The Password field should be filled in, if not just put it in again.

Scroll down.

Leave "Domain" blank.

Scroll down.

Leave "Save password" checked.

Under "Server address" put m.google.com

Leave "This server requires an encrypted (SSL) connection" checked.

Select "Next"

If all options are selected, deselect Tasks (Very Important!)

If not, select Mail, Contacts, Calendar

Hit Advanced Settings

Peak time and Non-peak time (I have "As items arrive" on both here) sets how often your emails are pushed to your phone.

I have nationwide coverage, so I also select "Sync data when roaming".

Hit "Done"

Hit "Done" again.

The phone will now connect to the Google Sync server and begin updating your contacts, calendar appointments and email. This may take a few minutes, depending on the number of contacts and such. If you have any unread messages in your gmail inbox, they should now appear on your phone in short order. You may choose "Send/Receive" from the mail Menu if you think it is taking too long.

You will now be able to receive your email sent to your gmail account as soon as it arrives. I have also forwarded my email from my other accounts to my gmail account, but this may be too much for you.

I would not recommend this to anyone who does not have the "Smart Phone" plan (so-called "Unlimited Data Plan"), as it will eat up your bandwith quickly. It may also have a detrimental effect on your battery, due to the fact that it requires a constant data and Active Sync connection to work properly.

If you are concerned about your battery, you can try changing the Peak and Non-peak options under "Advanced" to longer intervals. If it makes a big difference in the life of your battery, I would love to hear about it here!

You can view the original Google Sync video and tutorial links here:

http://www.google.com/mobile/sync/

Hopefully this will be of use to someone out there! Please let me know if you use Google Sync or if you have trouble following my directions.

---Issue With Labels/Folders---

If you have set gmail to tag messages with labels as they come in, you may not be able to read the messages on your phone. XDA-DEV user pantyshot has managed a workaround and posted it here. Be sure to thank pantyshot for the fix if you find it handy!