Last week we finaly decided to make the move to gmail. Our current email server has been humming along for the last 4 years, it was only a matter of time before something was going to go wrong. We have been using a combination of our own IMAP server running on a G4, yes a G4 xServe and Microsoft's Frontbridge for spam and virus protection. Initially the transition was smooth, a few DNS changes and we were up and running on gmail, sweet. Then came the migration of my 15 years of email, not a problem Google has a tool for that, it did take a while (hours), I had 10gb of mail (I delete a lot, sorta my workflow). Everything looked OK when I logged in from a web browser. Then the fun started, I opened my Mac Mail program, created a new account for my gmail and let the IMPA synch begin.
I left for some dinner, when I arrived back, I had a message that I ran out of disk space, I panicked a bit since some years ago I had a similar experience and my MacBook was never the same. I quickly dumped a bagillion pictures to my backup (I have been meaning to do that anyway) and let the sync finish. But I was curious, I knew I had about 10gb of mail, and when I started the sync, I checked and I had about 25gb available on my drive, hmmm something is not right so I started digging around to locate the culprit.
First I did a ï£¿i on my old IMAP and the new gmail IMAP directories, wow gmail was 3x larger! (gmail on the left)
Pretty strange! so more exploration, looking around my Mac Mail app I noticed this,
Ah-ah, that makes sense, well sorta, why would Google have 3 copies of the same email, it's tripling my mail? and upon a little further looking, I found that emails were sometime 4x and 5x repeated (mostly due to some messy old filtering on my part). wow. Not very Googley. I did a little thinking and in a bold move I selected the migrated "Lable" in my browser based email and deleted the reference to that label, re-synced from the Mac client and low and behold my gmail box fell to 20gb.
Why did this happen, well I have no idea why there is a migrated folder for the email, that's a Google thing (and customer service did inform us to hide the label, 3 days after we filed a ticket). As the years evolved using email, thru many different clients, I created a lot of sub directories on my old IMAP server, this at the time, was a good way of dealing with hundreds of email a day, I had filters that would move junk, 2nd, 3rd and 4th level email messages so the the primary important stuff was findable.
Google while they support IMAP, does not work the old way, the approach to IMAP is by creating lables, and you can use filters to apply lables, but the messages never get moved into subdirectories. The apple mail client is configured to work like the older style IMAP servers and would make a copy of the emails in your gmail Inbox into the subdirectories, leaving a copy in your Inbox and then duplicating the "migrated" and "allmail" labeled emails into those subs, as well as making additional copies into your other IMAP subdirectories.
So when I have some time I am going to remove most of the older IMAP folders and replace them with Mac Mail smart filters, I have used smart filter pretty much exclusivly for the last few years, but still left the old folder structure inplace, just because. Then I plan to create similar filters to match the desktop client.
Yeah some may say why use the desktop client, for me, it is still a lot faster to scan and delete (a workflow I have been using for a long time) in the client than in the browser. maybe over time I will change my workflow to browser only.
My Advice, once the migration of your email is complete, clean up any of the IMAP directories using gmail in your browser, remove the migrated labelÂ (I haven't removed the "allmail" label yet) and then sync, it will save you a massive headache and time.
Update, I also made these recommended settings from Google