The only desktop email client I am familiar with is Outlook. Outlook allows the user to attach an email to another email. In fact it allows multiple nested emails with attachments. May I know if this feature a standard as like SMTP, IMAP and POP? Or is it just a MS feature?
EDIT: I asked because I have some users having problems with this like blank mails etc so I suspect some mail servers are parsing the content incorrectly somehow. I am personally against this practice because i feel it breaks the architecture/structure of the email-vs-attachment relationship. Also, I found Attaching Email in Lotus Notes 8 tells me that lotus notes does not support it.
So I am wondering if I should preach it as a non-recommended practice.
EDIT: Ok, I found this... http://www.w3.org/Protocols/rfc1341/7_3_Message.html but I also found many issues about malformed headers. etc. Surprises me that out of such a matured protocol, there still exist a part where mail clients and servers have trouble with.