I have successfully been testing Aspose.Email with SharePoint 2010 using a C# custom action to read .msg files that have been uploaded to a document set. I have seen two issues when running the custom action - firstly the msg.BodyHtml output sometimes causes an invalid text error when copied to a enhanced multiline text field (msg.Body is always okay). Secondly, if an msg file has msg attachments then I get an 'Object reference not set...' error.
There are a number of reported issues with 'mail with mail attachments' in the forum but none specifically for SharePoint...this is the closest to my issue...
Do you have any sample SharePoint code for this similar to the .NET sample in the link above?