SMTP and IMAP server library for .NET

Question

Does anyone know a good SMTP/IMAP server library for C#?

I only found some long abandoned projects.

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Only SERVER SIDE libraries, please no more posts about client libs.

Thanks, Fionn

Hygrometry

Do you need the library to be able to do special tasks, like Queue mail for mass mailings? – Liquefacient

Answer 1

I am working on a project where I need to receive a mail via SMTP on the local network (a legacy application is sending a mail for integration purposes). Originally, I was going to use the SMTP server in IIS and use event sinks but that seems a little heavy-handed. I am currently evaluating the following 3 candidate libraries:

nDumbster: Open source but not a fully-implemented server. Originally used for unit tests. It parses the mail to an object for easy inspection. I had to revise it to raise an event when a message was received.

SmtpServer: Modern design using .NET TPL and Implements STARTTLS. Source code does not seem readily available. Provides a few hooks when message is received but appears to hand you the message contents as a blob. (I didn't get to test this as it requires .net 4.5)

Rnwood.SmtpServer: Looks to be full-featured and source code is available although documentation is lacking.

Beilul

Answer 2

LumiSoft.Net, a library from the LumiSoft mail server, is a free server side library. The server classes (e.g. IMAP Server, POP3 Server and SMTP Server) fire events when they need information or action for your server application, for example "give me a list of messages in virtual folder XXY".

Download Page

Carrillo

Still looking for something open source but until something better appears I'll try this. – Hygrometry

@Hygrometry It appears that the LumiSoft source code is here: github.com/pruiz/LumiSoft.Net There also seems to be a port to .NET Core here: github.com/ststeiger/Lumisoft.Net.Core – Dandle

Answer 3

I've used DotNetOpenMail in the past.

Vitality

Same here, i am talking about server stuff. – Hygrometry

Answer 4

You didn't mention whether you are looking for free or paid/commercial. I have used IPWorks from nsoftware with great success in the past.

Teredo

Answer 5

Also found https://github.com/cosullivan/SmtpServer, which seems to be a modern implementation of an SMTP (though no IMAP support):

SmtpServer is a simple, but highly functional SMTP server implementation. Written entirely in C# it takes full advantage of the .NET TPL to achieve maximum performance.

https://github.com/cosullivan/SmtpServer?tab=readme-ov-file

Gomar

Oh this seems to be the same as "SmtpServer" mentioned in the currently accepted answer sorry. – Gomar

Answer 6

For SMTP, there's System.Net.Mail. For IMAP, I don't know. But once you fetch the email from the server, you'll want to parse it. The MIME parsing is the hard part. For that, I use, and recommend, SharpMimeTools.

Toadflax

I am asking for server libraries, client is not the problem. – Hygrometry

This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. – Vena

@Vena There was a time way back when StackOverflow didn't have comments - this may be from then. – Bench

@Bench it seems comments were existing when the question was asked on Oct 30 '08 (almost there is one). Then perhaps this answer is obsolete as question precise now it concerns server side library. – Vena