gmailsmtp
I have both the default Gmail SMTP and my company's SMTP configured in Gmail. My company has asked that I always send emails to them using their SMTP and from address. But for general communication to other people I'd like to use my Gmail address.
Is there some way to auto mark certain To: addresses to use a certain From: or at least warn me?
You can do that from Settings > Accounts and Imports and select Reply from the same address the message was sent to:
Configure MX records in your domain :
When you’re switching to Google Apps and you want to receive emails in Google Mail (Gmail), you’ll need to point your MX records to the Google mail servers.
You modify MX records using the administration tools of your domain host and not the Google Admin panel.
Be aware it may take up to 72 hours before changes are propagated, depending on the TTL that was configured for your MX records.
Best Answer
There is not an explicit way of doing that, but it is a realy fantastic idea that you should sugest to the Gmail team.
http://mail.google.com/support/bin/static.py?page=suggestions.cs&issue=116880&bucket=16937
I work in the same way with both emails is Outlook and you just need to get into the habit of checking the "From" address before you click send. Enabling the "Undo" lab goes a long way to rectifying mistakes.