title: System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable in sharepoint 2007
body: <p>I have created a document library in sharepoint 2007 and i have enabled incoming email settings to the doc library. When I am trying to send an email from workflow I am getting the error... </p>
  
  <p>System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: 5.7.1 Unable to relay for  EmailDocLibrary@xxx.com 
     at System.Net.Mail.SmtpClient.Send(MailMessage message) 
     at DP.Sharepoint.Workflow.Common.SendMailWi</p>
  
  <p>Do i need to setup anything before sending an email. Please help me.</p>
  
  <p>Thanks</p>