[icey]

It is not illegal to drop emails.

That being said, are you positive the problem is with hotmail itself and not its mail handlers?

For example, if you use the incorrect sort of line breaks [1] in an email that gets sent to a qmail server, the server will silently drop that email message. It will report an error textually but not return an actual error code. This could make it look like your email was getting dropped. This happens quite frequently with machine generated emails.

Who knows if MSN / Hotmail uses qmail, but my point is that there may be other matters afoot than Hotmail intentionally playing hardball with you.

[1] Qmail pukes when you send an email that contains carriage returns without line feeds.