[BUG] Email address with special characters: MISSING CONTACT

[Goth]

I have a contact with an email address which starts with the characters ||_ and ends with _||
With MSN I can see it, with aMSN I can't. He doesn't appear neither in the various "Preference->Privacy" lists.
I suspect that aMSN is not capable to read weird characters in the email address of the contacts and so it doesn't process those contacts at all.
Or maybe it's totally another thing, maybe he is using a particular client, I don't know, so I'm posting here to discuss about it and not on the bug report.

[BW]

Hi Goth,

so the email address is something like this?
||_User.name_||@example.com

according to Wikipedia, this would be a valid email address;
the problem is, at the moment Windows Live IDs and Yahoo don't allow
Accounts with special characters except
periods (.), hyphens (-), and underscores (_)

[Goth]

And so what that means?
I consider a missing contact a serious problem.
Any way to solve it? Have I to post it in the bug report?
Why can I see this contact with the official version of MSN with no problems at all?
Thanks for reply.

[Goth]

UPDATE: the guy can write to me; it seems though I can't write to him. Its email address in the chat window appears correctly, but stille I can't find it in the contacts list neither in the privacy setting list.
I can understand it's a bit tricky to debug this, but really anyone from the devs?