RunSignup Referral Rewards Program is one of the best ways to increase viral participation. You can reward participants to promote your race by offering them partial or full refunds when they get X number of their friends to sign up for your race.
Now we make it simple for races that use our MailChimp integration to pass those referral codes and links to MailChimp. This allows your MailChimp emails to include those custom links to encourage participants to invite their friends.
To set this, use the same field integration capability described in the previous blog post in MailChimp integration. The instructions are found on the RunSignup Dashboard on the MailChimp setup page. There are a long list of data fields from RunSignup that you can pass over:

Log into your MailChimp account and pick a list and then click on Settings -> List fields and *|MERGE|* tags. On that page, add fields, enter a name for them (like Race Page Link), and then the corresponding tags in RunSignup (like RSU_RACLNK).

The RSU_REGLNK is a link to the signup page and includes the participant’s referral code if they have one. RSU_RACLNK is a link to the RunSignup race website and includes the participant’s referral code.
When you look at a participant in MailChimp you will see those fields:

The one note is that if you have previously synced a participant to a list in MailChimp, this will NOT update the referral links. You will have to create a new list and then resync. Remember, participants can be synced dynamically as they register (syncs every 5 minutes) or by exporting a participant report.