We have enterprise users that want to try out an online mail provider (such as GMail or MS Exchange Online) for a trial period, but would also like their local mail (Lotus Notes) to remain synched with the trial account so that they can compare and contrast and maintain their normal work routine both in the cloud account and in their 'local' accounts.
What is the best way to achieve a seamless 'mirroring' of both email accounts for each user so that
- emails delivered to either account will appear in the inbox of both accounts
- emails sent from either account appear in on both accounts in the 'sent items' folder
- emails moved from one folder to another in one account will automatically reflect on the other account (this is a 'nice-to-have').
The key word here is seamless. Emails sent/delivered to/from either account should retain their original senders and sendees.
Is this even possible?
Seamless is only going to happen if you can synchronize email between Gmail and Domino and regardless of what's possible, a two-way synchronization is - at best - going to be problematic. What happens when one of your test users tries to move a message to a folder on Gmail and simultaneously moves the same message to another folder in your usual email client? (What are you using as a client for Notes, BTW?)
If you were talking about Gmail and Outlook/Exchange, you can use Outlook as an IMAP client to Gmail and do the synchronization that way. But going the other way, I have never heard of Gmail being used as an IMAP client, talking to your Domino server.
If it were me, to avoid any risk of someone's "real" email getting screwed up, I would simply forward a copy of all their incoming mail to a GMail account and let them work with the copy. I'd set a reply-to address on the GMail account so that mail comes back to your servers (and a copy sent out to Gmail again), set up a signature block to announce the testing, and configure Gmail to CC: outgoing messages back to your server. It's kludgy, but for testing purposes, I'd rather be safe.
I try this using MS office 365 Beta and have mails sent to my local from there and vice-versa. The problem is that users will eventully lose track of where what mail came from where and this could screw things up from a professional perspective. For example, a user goes the risk of sending vital mail from a test account to a client and once the test is over, the client may continue sending vital mail to an account that no longer exist. Not much of a problem to correct but the chances of confusion working out of two mailbox is a bit much when considering we have other things to do.
Besides, online accounts don't have the features like an enterprise mailsystem such as groupwise, exchange, lotus, etc.. Maybe googlemail comes close to inhouse systems but even here you have limits. However, judging from your intent, you seem to be playing with the idea of cloud services anyway. Since your users already know your local mailsystem, just having their mails forwarded to an online account in question to work from for a limited period should be enough to become familiar with the new look and features of a cloud service.
This way they don"t have to worry about which account they work from but rather how long it will take before they will test before throwing in the towel. If you have a select number of testers willing to "neglect" using their local accounts for a determined period of time, then your test period will be less time consuming, confusing and more productive.
Another thing - if you find an online mail provider that offers you anything closeto what you want, then the concept employed by Thunderbird is similar to what you will get and that would be an awesome testing platform.