Can we add Custom Headers to the received mails through IMAP?

Question

We want to add a Custom Header to each received email and archive it using imap. We want to know,whether we can do this using Rebex IMAP. We are planning to purchase the software.

Answer 1

The IMAP protocol doesn't make it possible to modify a message at the IMAP server. However, you can download the message, modify it, and then optionally re-upload it (in case you would like to archive it on the IMAP server).

For information on how to download messages, please see IMAP - message operations and check out the ImapDownloader sample that comes with Rebex Secure Mail install package.

To add a header to a downloaded message, the most efficient method would be to use the low-level MimeMessage class with OnlyParseHeaders option:

var message = new MimeMessage();
message.Options = MimeOptions.OnlyParseHeaders;
message.Load(path);
message.Headers.Add("X-My-Custom-Header", "Custom header value");
message.Save(path);

(Although, for more complex operations, the high-level MailMessage class is usually more suitable.)