verbal checksum

I, like many people, frequently have to give an email address over the phone. As those of you unfortunate enough to have to do this know, you have three options at the moment:
1)Spell it out and hope they get it right (they will not, even if your name is john smith)
2)Try to remember the whole A=alpha, B=bravo thing, or make your own (I use animal names, which is fun, but equally confusing when you get to 'Q'). One major downside to this is I am always nervous I might accidentally say the first word that comes to mind: “N as in Nipple”, or some other similar embarrassing statement.
3) Get a simple email address (which will still get screwed up)
I propose a system of mentally computable checksums. It will not be fool-proof, and there will be a high chance of collision, but if it is generated logically and with care, it could be quite useful.
It could also be implemented in email software for increased ease, so after the recipient has typed the address, they are presented with the checksum to verify
Verbal communication would go as such:
"My email address is fred-savage@fakemail.com. My checksum is 64".
The checksum computation will be so easy as to allow for most people to do it in their heads, or at least with a few seconds and the place next to where they wrote the address down.
How the checksum might be ordered:
Letters that sound alike should be separated and given separate values.
Value:letter,letter,etc
2:A, B, F, G, H, I,
3:C, J, L, M
4:D, K, N, O
5:E, U, S
6:P, R, W
7:Q, T, X, Z
8:V, Y
Periods, Spaces, @ symbol, and numbers go uncounted, as they aren’t easily confused. Also, the TLDs (.com, net, etc) are not counted, however odd ones and country-coded ones are (.cx, .cc, .us, etc) It would be extra helpful if the values were memorable, some of these are not
Upon hearing the email and checksum, the recipient adds up the relevant numbers and if they do not match the checksum, it is known that the email address was not interpreted properly. Obviously, there exists the chance that if two or more letters are interpreted wrongly, the checksum can come out right. The only way to fix this problem is to expand the size of the checksum, which defeats the purpose of being relatively simple.
Obviously it will be tough for some people to add up 20 small numbers, so email software will have to incorporate this idea and have a running checksum next to the address bar, after, of course, having decided on a standard. I fear that there would be several different standards, and it would indeed be annoying to have to specify which checksum you’ve implemented.

Note: The checksum formula I've included here does not include the use of letters, which would expand the dictionary and lower collisions – Using some letters may be okay, but care would have to be taken to ensure that the original problem of undifferentiable letters is not reproduced! i.e. use only the letters X, R, O, W, H, Y, L. Words could also be used, but remembering their values would be difficult. “What does ‘rabbit’ equate to again?” also, how do they get added in?