Failure email becomes unformatted

I am sending email using asp.net and it is working fine. But when an email gets failure to deliver then the failure email which i get becomes unformatted.

the email contents are in html format and attached .doc files. i am smtp for sending emails.

i think that, this is 开发者_如何学编程not because of code i am using to send email so i am not putting sending code here.

Please suggest me what should i check.

Thanks

Mail failure of mail sending is because of your smtp configuration or by data transportation blockage. and this will read your attachment as byte[] so its only the reason to make sure that your smtp configuration is well working...