With the latest version of SugarCRM you can allow your users to set their own Outgoing Email Settings and send emails via their own email account.

For the purpose you need to login to your SugarCRM application with your administration account, click on the Admin link displayed in the top right to open the administrative section. From this page go to the Email Settings section and make sure that this option is unchecked:

Allow users to use this account for outgoing email

Having this option unchecked allows your users to set their own Outgoing Email Settings for the emails they send through the system.

In order to change the Outgoing Email Settings, the user should login and load the Emails module, and open the Settings window.

At the bottom of the window there is a section called "Outgoing SMTP Mail Servers". By clicking on the Add button a new window will be loaded providing the user with fields that should be set to the email account of the user.