Webmail stripping out email addresses in forwarded emails

[#1]

Difficult to illustrate this since I don't want to publish people's email addresses - but I've found forwarding emails using webmail that the "To" and "Cc"  fields are often blank or incomplete. There's a small snapshot attached showing a blank To field as an example - so the person receiving the forwarded email can't see who it's from. I've confirmed the information has been stripped out and is not just hidden by examining the coding using the HTML button.
Is this a bug?

[#2]

How often is "often" in the phrase "often blank or incomplete"?
I've just tried forwarding 3 emails, one with multiple To addresses, one single address, and one with attachments and the From and To fields were all correct (didn't have a CC readily to hand)? This is composing in HTML.

[#3]

I tried several before posting the query. Admittedly I hadn't noticed it before but it's only recently I've been using webmail rather than OE for such emails as opposed to just responding to a single person.
It appears to affect the second forward. Really difficult to explain without giving examples. Try forwarding an email to you then forwarding or responding to it again - the original email addresses are the ones affected.
The reason I was using forward instead to reply to was that the latter inconveniently strips out the entire header leaving just "On 2013-01-29 18:19, xxxxxx@btinternet.com wrote:" so it doesn't then record the other people the original email was sent to. I thought forwarding would be a way of getting round this but clearly there's a bug there which strips SOME of the info out but leaves the fields there.
I'll PM one to spraxyt Just discovered I can't add images to PMs.

[#4]

Right - here's an example. I received a voucher from TableTable so forwarded it to my brother. Then I tried forwarding that forward and look, in the original email the from and to fields are both blanked out. Surely that's not meant to happen - is it?

[#5]

From a quick experiment,  I can confirm it is really happening,  and if you watch carefully,  you should see the effect every time!
It appears to be an issue with the HTML editor, and is caused by a parsing error.
In the first email you receive,  the to/from email addresses in the Original Message are surrounded by angle brackets.
When generating the new message,  these appear to be interpreted as invalid syntax and discarded.
In other messages, where the to/from addresses also have a name present, (e.g.  from:fred <fred@example.com>),  you should see that again,  the email  address is stripped when forwarded,  but the name is left.