Mailbox Restrictions

• Your email administrator grants permission rights to your mailbox. For example, you may have rights to send to any email address, or you could only have permission to send to internal email addresses within your company. Ask your email administrator to verify that your permission levels are adequate to send to the desired email address. If not, he can make the necessary adjustments.
  
  

Sending From Another Mailbox

• Outlook enables you to grant another user the rights to send email on your behalf. This feature is often used by assistants who need to send emails for supervisors, or when one employee needs to cover for a coworker who is out of the office for an extended time period. Open your "Sent" items folder in Outlook and check the message that the error bounce-back message refers to. Notice the "From" field in the email and verify that you haven't inadvertently attempted to send email from an account other than your own. If another person's name is in the "From" field, resend the email leaving the "From" field blank, which will default to sending the email from your own mailbox. If you do need to send an email on behalf of another person, have that person, or your email administrator, grant you the necessary access.
  
  

Distribution Lists

• Outlook allows you to create distribution lists for convenience when frequently sending emails to the same group of email addresses. If a distribution list contains a large number of members, Outlook may have difficulty expanding the group and will return the bounce-back error message as a result. The solution is to send the desired email without using a distribution list. You can also mention this error to your email administrator who can check that your email server software is up to date.
  
  

Email Syntax Errors

• Syntax errors, or mistakes in the formatting of an email address, will cause the error bounce-back message. For example, an inadvertent space before the "@" symbol, or the use of a foreign character such as a "u" with an umlaut or an "e" with an accent. To solve the problem, resend the email after correcting these formatting errors. Consider changing the contact entries in your address book to prevent future issues.