I have a client who has three people working in different locations. They use the webmail system hosted with their site as all three need to access all the mail boxes.

 

It is currently set up so that they imap the mail folders to their individual machines using thunderbird which seems a bit clumsey for archiving older folders and a bit of a faff to mark folders for offline storage.

 

Any suggestions would be most welcome?

For Business grade I'd always recommend Outlook. I use 2007, and minus a few minor issues now and then, it suits perfectly. For alternatives, Thunderbird was second best, but I found Windows Mail's simplicity quite good (wouldn't recommend for business use though).

 

1. Outlook

2. Thunderbird

3. Windows Mail

 

But that's my limited usage of email clients - there may be better I've never used before.

I'd recommend Thunderbird.