From email addresses with 4 character domain names or non-normal domains
The most likely cause of this error is that the email was entered in the format myname@example.org rather than a name and email in the format My Name &lt;myname@example.org&gt;.

While the field label at civicrm/admin/options/from_email_address?reset=1 says From Email Address, the field actually requires you to enter a sender name and email address.

The field help says,


  Include double-quotes (") around the name and angle-brackets (&lt; >) around the email address. 
  EXAMPLE: "Client Services"