At about the same time that I was sorting out syncing my computers, I also changed the way I receive, send and archive email. I'd read an article on CatCubed which described how to route all your email through Gmail, while retaining the ability to send email using your own email address. It combined the benefits of being able to use IMAP in a desktop email client, while having access to Gmail's excellent web email client on the road. As a bonus, with the enormous storage quotas you get at Gmail, you can leave all your email archived there for access from anywhere, and also make use of the brilliant spam filter on the server side. Since several of my email accounts have really miserly quotas, and I like to archive most of my email, I've often found that I've gone over quota in the past, which has caused a lot of hassle. Hopefully, that should never happen again. The rate at which Google is adding storage capacity to my account is currently outstripping how quickly I can fill it.
The instructions are quite involved, but simple in principle. To make things a bit more complicated, I wanted to filter three different email accounts through Gmail, and retain the ability to respond to or send emails as if they came from any of the original accounts. That part turned out to be relatively easy. I just used the Settings > Accounts section of Gmail to check mail from each of the accounts to pull it into the system, labelled it appropriately so that I had a record of which account it came to, and forwarded it on to the private IMAP address that I'd set up according to the CatCubed article. Then in Apple's Mail, I set up the private email account, listing all three of my original email addresses in the email address field. That way I get a drop down menu when I compose an email, allowing me to select the correct address. You can send everything via Gmail's SMTP server (I had previously set up Gmail to be able to send email as if it came from my three original email accounts). However, the problem is that Gmail alters one of the email headers (either From: or Reply-to:, I can't remember which) so that MS Exchange users see your Gmail email address as well as the email address you are trying to send from. Now I just send email from my private IMAP account and BCC to the sending email address, and have a filter in Gmail to skip the inbox for those emails. Magically, Gmail files them away in the Sent mailbox (even though they weren't sent from the Gmail address), so you can search for them there.
That was all working fairly well, with a bit of tinkering of filters, but then a couple of weeks ago, Gmail introduced the facility to use IMAP rather than POP for its accounts. With some trepidation, I set that up, and it has simplified things quite a bit. It means that I don't have to forward my email from Gmail to my private IMAP address (which is now a send-only account), and I have access to all of my archived Gmail, including my labelled folders, from Apple Mail, which is very nice. Because of the way that Gmail works, if you don't map the Trash mailbox to your local Mail trash, 'deleting' an email from a mailbox just removes it from that mailbox and it still exists in your 'All mail' mailbox on Gmail. I have three 'Pending' mailboxes on my Gmail account (one for each of my original accounts), into which I place any emails that I need to deal with, but don't have time to deal with right now. When I've responded to them, I can just delete the email without worrying about filing it somewhere appropriate, in the knowledge that it will still be safely tucked away in 'All mail', and I can find it if necessary with Gmail's excellent search facility. It makes for a very smooth workflow, and there's a certain satisfaction to be had from gaily deleting stuff in your inbox!
Of course, I am putting a bit of faith in Google to live up to their mission statement 'not to be evil', so I have a belt and braces approach that would allow me to retrieve my email should things Go Wrong. I've used MailSteward for some time to make archives of my email as a backup. You can create multiple databases, search within them quickly, and also export in a number of different formats, so you always know that you'll have access to your email. Every day, MailSteward copies any new email to its database (it can ignore duplicates), so that I've always got a backup that I copy to other disks to act as a yearly archive.