t-maxx cowboy's Journal: Use GMail to eliminate duplicate e-mail.

Last night I was playing with one of my Google Apps (Gmail) e-mail accounts and discovered a feature that does not seem to be publicized at all, though does seem to appear in searches of the Google Support forums. Gmail automatically filters duplicate e-mail and keeps only one copy of each duplicated e-mail.

I had previously enabled the IMAP support on my Google provided mail accounts. It wasn't until just last night while I was copying some of my IMAP folders from my private IMAP server to the Google mail servers I noticed that the folders on the Gmail account (within my Mail client, so this is not a case of Gmail conversations) had a lower count of e-mail than the private IMAP server folders had. Upon investigation, I confirmed that the reason the count for the e-mail in the Gmail folder was smaller than the private IMAP server folder was because, there were perfect duplicate e-mail sitting in the private IMAP server folder. Gmail had automatically detected the duplicate e-mail and proceeded to toss away almost all duplicate copies keeping only one copy of each duplicated e-mail. This was verified on multiple IMAP folders as I copied them over.

Further information about this process was discovered, when I went to the Gmail website and logged into the same account and took a look at some of the folders. Of course the e-mail count for the folders was different from my local mail client because of the Gmail conversations feature. However I also noticed that some of the e-mail I had previously filed into my private IMAP server also had existed in other folders or even my INBOX which had previously been copied to Gmail. How did I notice this? Well it was quite simple, I realized that Gmail was showing the Inbox label and/or other labels for some of the e-mail in one of the labels (folders) that had just been copied from my private IMAP server. This would indicate that Gmail noticed some of these e-mail were actually duplicates of other e-mail in the entire mail account and not only within the folder that was just created and copied over.

I rate this as a cool feature, as it has been shown to be an effective duplicate e-mail detection system. It has helped me because over the years, the multiple backups I have made of e-mail have often resulted in many duplicates that I had to sort out manually, when ever I had to import archived e-mail, due to a e-mail application crash or hard drive crash.