I needed to replace the Easymail IMAP client component that my company uses because it doesn’t support imbricated forwarded attachment ( an attachment which is a mail containing an attachment which is mail containing an attachment which is a mail, …)

I found different IMAP clients :

1. The one which looked better a first was the n-software Ip*Works solution (www.nsoftware.com). This IMAP component is really well designed and support imbricated attachments. However, it appeared that it is not thread safe. Calling a method of the IMAP class from a thread different from the one in which the class was instanciated causes strange behaviour ( slow answer from the server). The n-software support confirmed it’s a known issue, and that it cannot be fixed. What a pity 🙁
2. I tried the Chilkat IMAP component (www.chilkatsoft.com/). It was presented as thread safe, and stress tested in ASP farms. Although the component is not really well designed, I tried it. But it appeared that it didn’t work with all the IMAP servers I tried (especially the Vircom Modus one), and in some cases it throws exception (access violation)  when the documentation said it shouldn’t. Moreover, in the very simple demo application I wrote. I had memory leaks even when only doing a login logout… I may have been unlucky with my tests, but I will avoid this component.
3. Finally, I tested a IMAP client from Hunny Soft (http://www.hunnysoft.com/mailpp/index.htm). First, I noticed that it was possible to purchase the source code of this component. And finally, this is the BIG WINNER ! It really is well designed, easy to use, efficient. It looks like it can be used in a multi thread context without problems. That’s the one I will recommend !