Automatically inserts HTML signatures into your Gmail messages based on which address you are sending from. Supports up to four signatures for each address you have set up. Works for Compose Message and Reply/Forward.Once installed, everything happens within Gmail itself (as seen in the screenshots above and below): Pick the email address you want to send your message "From" > insert the (HTML) signature you want to use for this account into the top box > save it > send your email. That's pretty much all it takes to setup. One of the nicest features is the ability to save up to 4 different signatures (Default, Business, Family, or Friends) for each email account. The only real drawback at the moment is the fact that you have to both use Firefox and have this add-on installed on each computer that you send email from. Clearly, this could be a deal-breaker for a lot of users. But if you always use Firefox, this free add-on provides a quick and easy signature "fix"...at least until Google adds this functionality to Gmail, itself.
official Gmail blog post a quick read. Now that you've got your multiple email addresses organized/setup under one umbrella account, you might also be looking for a way to create unique email signatures for each account. Unfortunately, at this point in time, Gmail does not provide this functionality natively. However, if you use Firefox, there is a rather simple solution via the free Mozilla add-on, Blank Canvas Gmail Signatures. This add-on: