Gmail has a behavior in place that redirects email in the event the destination email address doesn't exist. For example, Johnny Appleseed (johnny.appleseed@gmail.com) misspelled his email address during registration as john.appleseed@gmail.com, which does not exist in Gmail's system. When this happens, Gmail notices the address does not exist, assumes a typo was made, and redirects messages to johnappleseed@gmail.com (punctuation removed), even though the intended email address is johnny.appleseed@gmail.com.

You may want to reach out to the constituent to verify their email address. If a change is necessary, then you can update the email address on their behalf.
  1. Navigate to Constituents360 > Constituents
  2. Find the Constituent record and click Edit
  3. Enter the correct email address within the Email field
  4. Click Save