Spanning Sync keeps contacts in your Mac OS X Address Book synchronized with your Gmail contacts. Contact names, street addresses, phone numbers, email addresses, IM addresses, job titles, notes, and pictures are synchronized.

Keeping your contacts synchronized with Spanning Sync is simple, but there is some subtlety to keep in mind.

Google does not support the same contact name and postal address fields that Address Book does. For example, Address Book allows you to specify a first, middle, and last name, but Google has just a single field for the entire name. There are two things you can do to prevent these differences from causing problems:

1. When turning contact syncing on, you can select a "compatibility mode":

   

   The first option, "Preserve Address Book data" is recommended for users syncing multiple Macs with one Google account using Spanning Sync because it guarantees that names and street addresses in Address Book maintain their formatting. For example, a first name "Vincent" and last name "Van Gogh" doesn't become first = "Vincent", middle = "Van", last = "Gogh". The downside is that the extra formatting may keep autocompletion from working as expected in Gmail and may cause unwanted characters to appear in other applications and devices.

   People who sync their Google contacts with other applications or devices should use Gmail compatibility mode.

2. When editing contact names and postal addresses, do so in Address Book and not in Gmail if you're using the Address Book compatibility mode. Deleting these fields in Gmail is fine, as is editing other fields such as email addresses and phone numbers.

3. Google considers every contact that you've ever emailed a contact, even if they don't have a name. Most people do not want these no-name contacts appearing in Address Book. For this reason, Spanning Sync will not sync contacts with no name.