The way in which a user’s e-mail is sent from within the Microsoft CRM is configured on the user profile in the Microsoft CRM.
CRM -> Settings -> Administration -> Users -> User Profile Record
For both the incoming and outgoing access types, you can select to have CRM e-mail activities use the E-mail Router (if installed), or Microsoft Dynamics CRM for Outlook to act as the sending agent. In CRM4, you can configure the CRM for Outlook to deliver standard Outlook e-mails, CRM-tracked e-mails, and e-mail activities created from within the CRM.
To allow CRM for Outlook client to send all CRM e-mail activities:
1) Navigate to CRM -> Settings -> Administration -> Users -> User Profile Record
2) Select Microsoft Dynamics CRM for Outlook on both Incoming and Outgoing e-mail access types in the E-mail Access Configuration for each User Profile Record that should use the CRM for Outlook to send CRM e-mail activities.
Click ‘Save and Close’
3) On each Outlook profile, open the Set Personal Options by clicking CRM -> Options
4) Switch to the E-mail tab
5) Under ‘Check how CRM for Outlook should integrate e-mail with Microsoft Dynamics CRM’ check on: Allow Microsoft Dynamics CRM to send e-mail using CRM for Outlook
When an e-mail activity is created and sent by that user, this e-mail activity will be sent through Outlook on next synchronization.