I use Gmail to manage my eleven different email accounts. I have all of my accounts set up as mail forwards (e.g. addison@cameronhuff.com forwards to myemail@gmail.com) and then SMTP for outgoing from Gmail. This set up allows me to have all of my different businesses funnelled into one account that's accessible on my phone and computer. When I reply to a message my email will be sent from the email address that it was sent to (and not the Gmail address).
Besides the incredible convenience of managing many email accounts through one, using Gmail gives me Google's anti-spam filters (they're great). Google anti-spam is also a great defence against phishing emails.
This set up works particularly well with an Android phone because the integration with Gmail is better.
How to set this up if you're a sole practitioner:
1. Set up a mail forward on your email server. This is probably through your web hosting. Forward to yourgmailaccount@gmail.com.
2. Add the email account to your Gmail. Make sure to send using SMTP. Here are instructions that should help: techspot.com/...
Small firms:
You can switch your email provider to Google Apps for Business and take advantage of Google's anti-spam/anti-phishing features. It costs $50/user/year.