Colon ( : ) Symbol is Swapped by an Underscore(_) in “from” Email Field

Problem statement

The colon (:) symbol is swapped by an underscore(_) in the “from” email field for email templates.


  1. Use colon (:) in the “from” field in the “Email Templates”.
  2. Send a test email.
  3. See that the colon is replaced by an underscore when receiving the email.


The value of the display name cannot have a colon due to possible conflicts with the header boundaries definition.

The implementation Auth0 uses makes a best effort and replaces the colon with an underscore; some other implementations might do the same but with a whitespace.

Related Reference