The free Contacts Sync utility automatically syncs entries in your Gmail and Outlook contacts, although some manual tweaking of duplicate and empty entries will likely be required.
A reader named Maribeth is migrating from Outlook to Gmail and asked about synchronizing her two accounts:
"I just read your blog about Outlook/Gmail [Merge your Outlook and Gmail contacts]. I understand this is a fix to make them both the same, but do you know if there is a way to sync them continually? I still want to use Outlook on my desktop and also have IMAP movability on my Droidx2 phone and also on an iPad. Is it possible?"
In a July 2009 post I described how to "Sync contacts and calendars between Outlook, Gmail, and iPhone." That post refers to the free Google Calendar Sync utility, but there's no equivalent from the company for syncing contacts. Google does offer its paying business customers Google Apps Sync for Microsoft Outlook (free trial available).
A potential alternative is the free Contacts Sync utility from Indian company PPP Infotech, which automatically syncs your Gmail and Outlook contacts. The only glitches I encountered in testing the program were Outlook's built-in antivirus protection, which required that I manually allow Contacts Sync to access Outlook's contacts, and the inability to sync contacts that lack data in the e-mail or last-name fields.
To sync your Gmail and Outlook contacts via Contacts Sync, enter your Gmail ID and password in the program's main screen and click the Save Settings button. Then select the Outlook folder to synchronize (likely All Contacts), choose one of the two sync options (Outlook contacts to Gmail or Gmail contacts to Outlook), and click the Synchronize button.
Contacts Sync first fetches the contacts in each system and then syncs the entries. As I mentioned, a warning popped up in Outlook asking me to grant the program access to the contacts and to specify the length of time for access (in 1-minute to 10-minute intervals).
To activate automatic syncs, check Enable Scheduled Synchronization in the Scheduled Synchronize area at the bottom of the Contacts Sync window. Enter the number of minutes between syncs and select one of the two options: Outlook contacts to Gmail, or Gmail contacts to Outlook. The sync's progress and results appear in a small window that pops up from the program's icon in the notification area.
In testing Contacts Sync the program occasionally failed to complete a sync and generated a message indicating that the log-in failed. But on subsequent tries--without reentering the log-in information--the sync completed successfully.
More importantly, Contacts Sync ignored Gmail contacts without data in the last-name or e-mail fields. For example, several Gmail contacts for businesses didn't appear in the Outlook contacts after a sync until I had entered something in the entry's last-name or e-mail fields.
The first few times Contacts Sync ran, several entries appeared in the Outlook contacts on my test PC with only a name or an e-mail address. Some of these appear to be the result of Gmail's tendency to add contacts automatically when you communicate with people. After I cleaned up these orphan entries in my Gmail contacts, the problem disappeared.
One other problem I encountered in testing was Contacts Sync's tendency to duplicate some Gmail contact entries in Outlook. This may have been related to entries that appear in more than one Gmail contacts folder. The duplications were eliminated by ensuring that entries appeared in only one Gmail folder, which may or may not be a practical solution for you.
Another option for dealing with duplicate entries is to use the free Outlook Duplicate Items Remover (ODIR) utility from the Dutch company Vaita. Note that the program works only with 32-bit versions of Outlook.
I would much rather deal with the occasional duplicate entry than to worry about contact data being lost as a result of a sync. The program did a good job of preserving the names, e-mail addresses, telephone numbers, and street addresses of contacts in Gmail and Outlook, but as I mentioned above, it appears to ignore Gmail entries without data in the last-name or e-mail fields.