Error when sending a ticket email in Web Help Desk

When you send an email to update a ticket, the following error message displays: 

Local address contains illegal character

1. Log in to the Web Help Desk Admin Console as an administrator.
2. Click Setup > E-Mail > Outgoing Mail Accounts. 
3. Click the targeted email account in the Outgoing Mail Accounts column.
4. In the Outgoing Mail Account tab, verify that the Web Help Desk E-Mail Address field does not contain an email address with invalid characters (such as http, www, and so on). 
5. Verify that the email address is correct.
6. Click Save to save your changes.