I certainly hope you don't have to use something like cPanel to set up alias' in your ISP mail system! Extremely complicated for normal users ( including me ), IMHO. But I think karl and I are talking about the same thing now. If your partner has an account that is an alias of your main account, he can get his mail by setting up that 'name' in his Mail app. But you would still get any of his stuff if you checked just before him because you, apparently, have the main account name set up in your Mail app.
What Karl and I are suggesting is that you set up Mail, on your machine, to not download mail from the main account. But create more aliases at the account that only you will receive by setting up an account in Mail for each of them.
The problem will be that the main account is already 'out there' and people will probably be using it. SPAMmers, for sure, but they'll eventually find any address, anyway. You should probably notify all your important contacts of your new address ( one of the aliases you set up ) and hope they all make the change. I don't know any easy way around this problem.
You may also find that your ISP has a limit on how many alias' you can have, so be careful about creating them willy-nilly(sp?).
I'm not so sure I'd suggest creating any address specifically named "webmaster" or even "info" as those are standard recipients for SPAM. Matter of fact, just about any 'dictionary' word will probably collect more SPAM than anything else you use. One important defense against SPAM is to never publish your address in plain text in any website you create. There are many ways to 'hash' the letters in html and still make them easy to display/read/use but not place the actual text in the html. Many don't even need anything like javascript which more people are turning off, anyway.
Briefly ( he said, cathing his breath ), here's what I think both Karl and I are suggesting.
Create the following alias' at your ISP:
francesnewmainaddress@yourdomain.com ( for general use )
francesinfoaddress@yourdomain.com ( for use by people who want 'info' )
franceswebmasteraddress@yourdomain.com ( for questions about your website )
francessecondaryaddress@yourdomain.com ( for whatever else you want/need )
francespartneraddress@yourdomain.com ( you already have done this, of course )
Now, in your copy of Mail ( or any other email app ), create accounts for all your newly created aliases, except the "francespartneraddress" alias. Now, do the same for your partner, except use only the "francespartneraddress". Your partner can now continue recieving only mail to that address, but you should never see any of your partners.*
*The biggest problem I see with this set up is that either of you can see what's in every mailbox if you really want to. Since every address has the exact same password, anyone with that password can get into any other mailbox. It will only be as private as the two people want to make it.
BTW, let me know if you're interested in a simple program that can obfuscate your address and even add a subject ( and more ) to any email that comes from one of your sites/pages. And it's free, I think!