To track the specific outlet from where you are getting the sign ups, you can add "?utm_source=XX" to the end of your link. For example add "?utm_source=twitter" to links that you are sharing out. Unfortunately this cannot be added to the events people are clicking from the Public Events Feed, but is available for all other links you are sharing out.
You are going to be able to access this information from the per shift csv download where you can see the origin links for volunteers.
Note: You can use the UTM parameters on your main page as well as the event pages. It will no longer show up in their URL when they navigate to your page, but it will show up in the shift exports.
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