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Sending Email with attachment in ASP.NET using SMTP Server

, 28 Jun 2005
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This article explains how to send a mail with attachment using SMTP server and how to configure the SMTP server.


This application demonstrates how to send mail with attachments using SMTP server and how to configure the default SMTP server. The System.Web.Mail namespace provides classes for sending email in .NET. The classes involved are MailMessage which manages the content of the mail message and MailAttachment which manages the mail attachments.

Setting SMTP server

Before running the application you need to confirm these server settings:

  1. Make sure that the SMTP server is running, only then it can relay mail. If not, open the IIS window, in IIS look for the "local computer" on the left side tree view under which you will see the "Default SMTP Virtual Server", if it is not available, then you need to install it.
  2. To configure "Default SMTP Virtual Server", right-click on it, go into "Properties", and select "Access" tab, and then click the "Relay" button. With "only the list below" radio button selected, you should see the local IP address: "", if it's not there, you need to add it.
  3. If you are using "localhost" or "" as the SmtpMail.SmtpServer, make sure "Anonymous access is allowed". To allow access, open up the IIS. Locate the SMTP virtual server, and right-click select Properties. On the Access tab, click the Authentication button. Make sure "Anonymous Access" is the only checkbox checked.
  4. Use real from and to addresses that exist on the SmtpMail.SmtpServer. Do not use invalid address.

Getting objects

Initially, we need to create a new object for the MailMessage class, we will call it "mailMessage". Then we set the From, To, Cc, Bcc, Subject and Body properties as well as the BodyFormat of this object to the values on our web form:

 /* Create a new blank MailMessage */
 MailMessage mailMessage = new MailMessage ();  
 mailMessage.From = txtSender.Text;
 mailMessage.To = txtReceiver.Text;
 mailMessage.Cc = txtCc.Text;
 mailMessage.Bcc = txtBcc.Text;
 mailMessage.Subject = txtSubject.Text;
 mailMessage.Body = txtBody.Text;
 /* Set the properties of the MailMessage to the
    values on the form  */
 if (rblMailFormat.SelectedItem.Text == "Text")
    mailMessage.BodyFormat = MailFormat.Text;
    mailMessage.BodyFormat = MailFormat.Html;

Making attachments

To make attachments we need to use the MailAttachment class and for this we create an object attach. The following block of code checks the Open File Dialogs of our web form (the Open File Dialog is an HTML file field control to which we've added the runat="server" property). If there is a value, the file is uploaded, saved on the server and added as an attachment to the email.

/* Beginning of Attachment1 process   & 
   Check the first open file dialog for a attachment */
if (inpAttachment1.PostedFile != null)
/* Get a reference to PostedFile object */
HttpPostedFile attFile = inpAttachment1.PostedFile;
 /* Get size of the file */
 int attachFileLength = attFile.ContentLength; 
 /* Make sure the size of the file is > 0  */
 if (attachFileLength > 0)
 /* Get the file name */
 strFileName = Path.GetFileName(inpAttachment1.PostedFile.FileName);
 /* Save the file on the server */      
 /* Create the email attachment with the uploaded file */
 MailAttachment attach = new MailAttachment(Server.MapPath(strFileName));
 /* Attach the newly created email attachment */      
 /* Store the attach filename so we can delete it later */
 attach1 = strFileName;

Now, we send the email with the attachments:

SmtpMail.SmtpServer = "";
SmtpMail.Send (mailMessage);

Finally, if the attachments are available then we need to delete it:

/* Delete the attachements if any */
 if (attach1 != null)
 if (attach2 != null)
 if (attach3 != null)

Various ways to set the SMTP Mail server:

SmtpMail.SmtpServer = "localhost"


SmtpMail.SmtpServer = ""


SmtpMail.SmtpServer.Insert( 0, 
    " or your mail server name here")

You need to replace "localhost" with the name or IP address of your SMTP Mail server on a Windows desktop computer or you can insert the server but "localhost" is the default value and it usually works.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Sivakumar Ramadoss
Web Developer
India India
Sivakumar Ramadoss (SIVA) is a Software Engineer for Adea International Pvt Ltd, Bangalore. His background is in developing relational databases and n-tier applications in Microsoft Technologies.

Comments and Discussions

QuestionASP.Net PinmemberMember 998846915-Apr-13 0:20 
Questionerror PinmemberHeba Kamel19-Oct-12 6:49 
QuestionHow to send a E-Mail PinmemberUvaraj$8828-May-12 11:09 
AnswerRe: How to send a E-Mail PinmemberAmalraj Ramesh2-Oct-12 21:05 
AnswerRe: How to send a E-Mail Pinmember_Amy8-Oct-12 1:58 
GeneralMy vote of 5 Pinmembermember6010-Apr-12 23:21 
QuestionThanks Pinmemberamolkhedekar1-Apr-12 21:11 
Generalthanks PinmemberMehmoodMemon14-Feb-12 3:25 
Questionhow to make a perminate receiving email? Pinmemberpellegm9-Feb-12 3:12 
GeneralMy vote of 4 PinmemberMember 822688117-Jan-12 3:36 
GeneralMy vote of 1 PinmemberShama Shahzadi8-Jul-11 1:12 
GeneralNot Working Pinmemberanas khan ahmed15-Oct-10 0:56 
Generalwhen run the apllication i found this error Pinmemberjessystar804-Aug-10 1:28 
Generalwindows authentication mode error Pinmemberabeelzymal31-Aug-09 6:29 
GeneralSMTP Virtual Server settings on windows 2008 server Pinmembermarkah_199913-Jul-09 6:06 
Generali get the error on the first line Inherits="EMailSample.SendMail" PinmemberMember 378537910-May-09 0:01 
GeneralI'm not understand why i get this configuration error... PinmemberSteammike4-Feb-09 22:10 
GeneralRelay Problem PinmemberSyed Adeel Zaidi23-Oct-08 11:31 
Generalerror... PinmemberBruceInFTL15-Jan-08 7:41 
QuestionSending attachment in Winforms app Pinmemberjlo1438-Mar-07 19:09 
GeneralHelp for understand - Urgent PinmemberYamiyahoo3-Dec-06 23:17 
Generalerror help- The server respond 5.7.1 unable to relay... PinmemberYamiyahoo3-Dec-06 23:12 
GeneralMail Server Pinmemberanisha1965-Nov-06 9:05 
GeneralRe: Mail Server Pinmembermanish srivastava11-Jan-07 10:20 
GeneralHelp me Pinmemberprinceamrooo7-Aug-06 13:34 
GeneralThanx Pinmemberyourasp.net4-Jul-06 4:49 
GeneralInvalid Mail Attachment ' '. PinmemberhexOffender22-May-06 6:20 
GeneralRe: Invalid Mail Attachment ' '. PinmemberSivakumar_Ramadoss3-Jun-06 4:03 
QuestionHow to retrieve an Attachment file from mail server. PinmemberHendrik (Chrysonite)3-May-06 0:47 
GeneralSMTP server running on remote machine Pinmemberf_baig786@hotmail.com9-Feb-06 20:03 
GeneralDelete files error Pinmemberaltug200522-Dec-05 8:49 
GeneralRe: Delete files error Pinmemberthaiasp21-Mar-06 1:38 
GeneralRe: Delete files error Pinmembermusicdsign19-Oct-06 21:39 
QuestionRe: Delete files error PinmemberVikram kshatriya13-Apr-08 18:47 
AnswerRe: Delete files error Pinmemberpradeep8423-May-08 1:56 
AnswerRe: Delete files error [modified] Pinmembergrossbommi4-Jun-08 2:06 
Questionhow to check SMTP server is alive using code Pinmembertiwari piyush24-Nov-05 3:22 
Generalnot delivering to address Pinmembersam_ten200127-Oct-05 23:52 
GeneralRe: not delivering to address Pinmembercdotpal9-Mar-06 3:38 
GeneralRe: not delivering to address PinmemberHemant K Jangid24-Apr-06 4:56 
GeneralRe: not delivering to address Pinmemberyourasp.net4-Jul-06 4:52 
GeneralThanks for the code PinsussRinda Kotagiri12-Jul-05 0:13 
GeneralSmtpServer.Insert -- mistake PinsussJakub Snopek11-Jul-05 6:46 
GeneralRe: SmtpServer.Insert -- mistake PinmemberSivakumar Ramadoss7-Sep-05 2:47 
GeneralRe: SmtpServer.Insert -- mistake Pinmembermstehle23-Nov-05 10:20 
GeneralRe: SmtpServer.Insert -- mistake Pinmemberericpaulin28-Nov-05 4:01 
QuestionWhat if your SMTP server requires you to login? Pinmembercbono200030-Jun-05 8:56 
AnswerRe: What if your SMTP server requires you to login? PinmemberCatalin Radoi6-Feb-06 1:01 

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