Update (31 March): Works again with new Gmail.
For business users who manage multiple email addresses in a single Gmail account.
This extension allows you to override the default From address in Gmail with a query string parameter called bu.
Here is an example of the extension at work:
In this example, the default from address is companydatatrees.net, but the 'bu' query string parameter specifies companydatatrees.com as the From domain. Therefore, Chrome extension looks for the email that ends in the domain companydatatrees.com and automatically selects it. You may also specify an exact email address in the 'bu' parameter, in case you have multiple emails from the same domain.
It is very helpful for Salesforce users with multiple accounts who need to send emails from addresses. Salesforce only allows integration with one (1) Google Apps Domain. On top of that, Gmail doesn't let you specify the From address. Therefore, you're always stuck sending mail from the same address. The way you work around this limitation is by installing this script and creating a formula field in Salesforce that opens a Gmail send window with the From query string parameter.
The Salesforce formula field should look like this:
HYPERLINK("https://mail.google.com/mail/?view=cm&fs=1&tf=1&to="& Email &"&shva=1&bu="& Business_Unit_Communicatnig_with__c &"&bcc="& $User.Email2SFDC__c ,"Send Email")