If you are an Access Hosted customer, check the following:
Windows settings
Confirm you have 32-bit Outlook installed. Dimensions is a 32-bit application and does not work with 64-bit Outlook. Contact your IT team if you need help with this.
Confirm that Outlook is selected as the default email application under Default apps in Control Panel.
Dimensions settings
Click System, then click User Records.
Click the relevant user and confirm the Email Setup is set to the correct option (SMTP or MAPI).
Click System > Options > System Control > System Format.
Confirm the System Email Defaults details are correct.
If the issue persists after checking all settings, contact support. See Get support in Dimensions.