As a browser, I use Mozilla Firefox, which is terrific, and have pretty much stopped using Internet Explorer. http://texturizer.net/firefox/index.html.
The Mozilla email client is called Thunderbird, which I haven't tried, but might be worth a look. Try here. http://texturizer.net/thunderbird/
However, I am wary of anything except Outlook, because the MS ActiveSync links into PDA's quite well. I think other clients may not sync up so well. Plus when I looked at IncrediMail, there was no way of exporting all the data back out if you didn't like it. That could be a major disadvantage.
Bramble - no matter how many times I uninstall and reinstall it, I keep getting silly errors like "the default mail client is not properly installed" when i click on email links. Then it appears to cure itself for a few days, before coming back again. Sometimes it just locks up on me and falls over for no reason other than me checking for mail. Like you, I've about a dozen accounts for both personal and business reasons and its generally fine - just these little things are annoying me.
Before anyone says it.... my machine has no viruses or spyware on it. So I dont know what the problem is, but I just wondered if people knew of a decent alternative : I'll give your suggestions a look at, thanks
RR - my wife had the same problems with her machine at work and after installing ALL the latest service packs (not just for OE), but for IE, XP etc - it went away.
These little irritations take on an intensity out of all proportion to their impact.
One other thing while we're discussing email clients etc. I use Mail Magic Monitor. Can't recommend it highly enough. Lets you know when you've got mail in any of your accounts and even gives a limited ability to view them prior to download. Even more useful, the ability to delete them before download!!!