Send eml files saved on disk

Question

I am creating eml's and saving them to a directory using procedure mentioned over here. I want to know how to send these eml files? I tried using SMTPClient class's object but it takes MailMessage object as its parameter and I couldn't find and way to create an object of type MailMessage using these saved eml files.

Answer 1

Loading an EML file correctly is not as easy as it looks. You can write an implementation working in 95% cases within few days. Remaining 5% would take at least several months ;-). I know, becase I involved in developing one.

Consider following dificulities:

• unicode emails
• right-to-left languages
• correcting malformed EML files caused by well known errors in popular mail clients and servers
• dealing with S/MIME (encrypted and signed email messages)
• dealing correctly with several methods of encoding attachments
• dealing with inline images and stylesheets embedded into HTML emails
• making sure that it parses correctly a MIME torture message from Mike Crispin (coauthor of Mime and IMAP RFCs)
• making sure that malformed message will not result in buffer overun or other application crash
• handling hierarchical messages (message with attached messages)
• making sure that it handles correctly very big emails

Maturing of such parser takes years and continuous feedback for it's users. Right now is no such parser included in the .NET Framework. Until it changes I would sugest getting a thrid party MIME parser from an established vendor.

Following code uses our Rebex Secure Mail component, but I'm sure that similar task could be replicated easily with components from other vendors as well.

The code is based on Mail Message tutorial.

// create an instance of MailMessage 
MailMessage message = new MailMessage();

// load the message from a local disk file 
message.Load("c:\\message.eml");

// send message
Smtp.Send(message, "smtp.example.org");

Answer 2

If you're a Microsoft shop and have an Exchange server anyway, then there's another solution which is much, much easier than everything else suggested here:

Each Exchange server has a pickup directory configured out of the box.
By default, it's %ExchangeInstallPath%TransportRoles\Pickup.

You just copy the .eml files to that directory, and Exchange automatically will send the mails.

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Read this TechNet article for more information:
Pickup directory and Replay directory