This happens when there is an invalid parameter in the "sender email address".  Typically this happens when [[S0:SITE_CONTACT_EMAIL]] is being used in a field in the event options of the TeamRaiser.  Since the DMARC update in August 2014, email addresses must come from valid site domains, but also the fields in the event options are attempting to use the literal entries. So the email system is trying to literally send to [[S0:SITE_CONTACT_EMAIL]] or any other entry in the field that isn't a valid email address.

To correct this you can either remove the S-tag and leave the space blank, or you can enter the email address itself.

To find these fields in the TeamRaiser settings, follow the steps below:
  1. Go to Fundraising > select TeamRaiser
  2. Click Edit next to the desired TeamRaiser
  3. Go to step 3. Select Event Options
  4. Click Edit Advanced Event Options under Related Actions
  5. Go to step b. Define Event Options
  6. Options 4,5 or 7 can all have email addresses populated in those fields.
If any of them contain an S-tag or any other inavlid characters that are not valid email addresses, then it will produce this error message.