Hello,

I have two installations, test environment and production environment, both with 7.04.02. In production environemnt, I cannot send email with async mode (in newsletter module), while in test environment I have no issues. Sync mode works in both cases. 

The error I got is this:

Message:Mailbox unavailable. The server response was: 5.1.1 : Recipient address rejected: User unknown in local recipient table

StackTrace:

   at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   at DotNetNuke.Services.Mail.Mail.SendMailInternal(MailMessage mailMessage, String subject, String body, MailPriority priority, MailFormat bodyFormat, Encoding bodyEncoding, IEnumerable`1 attachments, String smtpServer, String smtpAuthentication, String smtpUsername, String smtpPassword, Boolean smtpEnableSSL)

Do you have a solution? Is it a known issue? The server smtp used is different, but I cannot believe that it is the cause of my issue....

Thanks

eclipse79

Well, they are correct. In fact if I test the smtp settings in host page, the email is sent successfully... and the newsletter is sent, using sync mode. Only async mode does not work... The settings used in both modes should be the same... isn't it?