You can add your custom UTM parameters to the links within your campaign content or template so that they can be tracked in Google Analytics.
For example, if you want to use:
- utm_source: promotion
- utm_medium: email
- utm_campaign: help_center
on one of your links, modify the link so it looks like this:
Check this tool to easily add campaign parameters to URLs so you can measure the email campaign performance in Google Analytics.