PlusNet domain hosting and email query

[#1]

Background:
I've had a .org.uk domain name with a domain name hosting company for many years (since before I joined PlusNet), which I have set to forward to my personal website with .Mac.
With new Apple software and a new .Mac facility, it is now possible to change the cname so that the address goes straight to an updated version of my website which I am currently working on, rather than using masked forwarding, but I've read elsewhere that if I do that, I will lose the function of the associated email address(es), which is just a forwarding address that I was able to set up to forward to one or more of my other addresses.
I don't want to transfer my domain name completely into my PlusNet account as for a non-.co.uk address it's considerably more expensive than what I'm paying now.
Question:
If I changed the nameservers so that PlusNet is just hosting the domain, would I be able to use the associated email address via PlusNet's mail servers in the same way as my PlusNet address and my free (after the Russian hacking) domain name address? Then, if I changed the cname to point to my .Mac website, would the email address still work at PlusNet, assuming I was able to use it already before changing the cname?
Any advice or help will be greatly appreciated!
(I've had a dig around both PlusNet's and the registrar's sites and found out how to do all the above but just need to know what will work and what won't with what looks the best solution!)

[#2]

I'm not sure what there is to gain from moving the hosting to Plusnet if your web site is with .Mac.
Are you sure that you will lose email functionality if you change the cname ? I have a .me.uk domain name registered with 123-REG with the cname pointing to my .Mac website created with iWeb. I am still able to use the associated email addresses, by forwarding them to another address, using the 123-REG control panel.

[#3]

I was thinking that if I was able to use the email address via PlusNet, then I would be able to reply to people using that same address rather than using one of my other addresses. At the moment the best I can do is to put the address in the 'Reply to' field.
Maybe I misunderstood what I read about email forwarding no longer being functional - might have been when you change DNS servers and not just the cname? I have the domain registered with Namesco (originally with Simply.com who they took over).
Thanks for your input, 'Ruslyn'. I only recently got iWeb 2 so the additional/revised bits of the site aren't quite ready yet and I've time to experiment. I'd rather the site was accessed using the domain name and I intend moving the original 'handwritten' bits of it from .homepage to .web so the whole lot can be together, and put redirects to my domain name where the old pages are at present so it gets into the search engines that way (did that before when I rewrote the site a few years back and it worked OK but eventually went back to only .homepage links appearing again).

[#4]

You can still reply to people using the email addresses of your domain rather than using one of your other addresses without transferring the hosting.
Lets say you want to use the address xyz@domain.uk You could create a Plusnet mailbox called XYZ and get all emails sent to xyz@domain.uk forwarded to xyz@plusnet-usename.plus.com. Then in Mail (or any other email client) create a new address with your email address quoted as xyz@domain.uk, your Username as plusnet-username+XYZ and your password being that which you created for the mailbox. Now when you send an email the addressee will just see it is from xyz@domain.uk with no mention of Plusnet or any other address.

[#5]

You mean spoofing the address? Will it still go out from here through the PlusNet mail system OK if I do that?
Oh yes, just added it to a PlusNet address even without creating a new mailbox or alias and it works OK without showing anything in the headers to say where it's from apart from my IP address! I've tried doing that  on my .mac address in the past and it doesn't work with their mail system - just refuses to send it. I suppose it works because the PlusNet servers don't need authentication. Oh well, I'll just set up a 'webmaster' mailbox and use the domain address and site name with that.
Thanks for pointing that out to me.
Namesco have web forwarding and email forwarding on the same control panel, which doesn't seem to give the option of turning web forwarding off, so I've now contacted them to see if email forwarding would be affected if I change the cname.

[#6]

I've had a reply from Namesco and the email forwarding won't be affected, as you said it probably wouldn't, 'Ruslyn'. So, it seems it will be a very straightforward matter of just changing the cname once the new bits of the site are ready for public consumption, and setting up a new PlusNet mailbox.
Thanks for the advice!

[#7]

Just be careful - if you have an email address fred@username.plus.com and an address fred@yoursite.org.uk the PlusNet system won't differentiate between the two so they will all come to fred@username.plus.com.
I don't know if this will affect what you are doing but it is worth checking.

[#8]

I'll probably be setting up a special 'webmaster' mailbox as that's anonymous enough! Don't have one of those as a mailbox or alias at the moment.