Question

I’m using .NET 3.5, and I want to automatically send a mail. I’m currently using the following:

Microsoft.Office.Interop.Outlook.MailItem mailMsg = 
    (Microsoft.Office.Interop.Outlook.MailItem)outlookApplication.CreateItem(
     Microsoft.Office.Interop.Outlook.OlItemType.olMailItem);
mailMsg.To = recipient;
mailMsg.Subject = subject;
mailMsg.Body = body;
mailMsg.Send();

However, I’ve found several articles that seem to imply I should be using the following method:

System.Net.Mail.MailMessage mailMsg = new System.Net.Mail.MailMessage();
mailmsg.To = recipient;
mailmsg.Subject = subject;
mailmsg.Body = body;

Can anyone tell me what the difference between the two namespaces if, and why you might want to use one over the other?

Answer 1

The second example needs a SMTP server, to make a direct connection, and uses this SMTP server to send the email. It has low overhead, will normally work.

If you need to compose & send an email on behalve of the current user, you could use outlook.

So far I have only seen answers with disadvantages for outlook. But it has a few advantages:

• You do not have to ask the user for any configuration.
  • Outlook already knows the Exchange / SMTP server,
  • and the email address of the user
• Email you send will be stored in the sent-items list of the user. So the user can see wat is sent in his name.
• Add-ons that sign / encrypt outgoing email, or add a standard company disclaimer will be used, so you will follow company policies
• Can prompt the user if it is allowed to send email (yes, this can be an advantage to)
• You can choose to only compose the mail, present it to the user. The user can edit and choose to send it or not.

Edit:
I use the SMTP method for sending technical emails (like log files & error messages) to our support unit, these mails go out fast and unnoticed.

The Outlook method I use for sending mails on behalve of my user to other humans. These mails are slow, but are trackable, etc.