Sold our home and need to keep a mailing address in Ontario

See if you find a postal center that is NOT considered a  PO box.   These charge a bit more but offer a more  helpful solution than the regular mail center.   I have used one for many years for certain legal matters.  Use one where your address will "look like" a residential address,  I have friends In Ontario and  will see what they have to say about this. Another option would be get an attorney for for a small annual fee to allow you to use his firm's address, assuming you would not be getting a lot of mail, plus postage for a monthly forwarding to a EXPAT mail service where ever you end up in Mexico;. 
Since I am close to the border I cross to a postal center in San Ysidro.

I don't know about Canada but using an attorney's address is working for a friend from  Australia now living in Fiji.

Hope this helps

Thanks Anne....I would be most interested in their suggestion as I've tried researching for such a place here but could only find a Quebec company.

Wny not call the Quebec company and see if they are aware of a  similar operation in Toronto or where ever you are.  I edited my comment with some additional input.

WOW....that worked really fast....Thanks Again Anne. I found a company and they charge $15/mo for the service. We have a good attorney we've used for a few years...never thought about asking him, but I am going to give that a try now.

Thanks so much everyone....

You may have had other reasons to require an address in Ontario.  Different countries have different rules, of course.

I, a US citizen, chose an address on the Texas border.
Florida had no hesitation mailing my drivers license to my "vacation" home at a private mail receiving company in Texas.  Their form for  addresses was Bldg 11 instead of Box 11. I renewed my passport through the US Consulate in Monterrey and it was couriered to me in Zacatecas.

I'm glad you made arrangements that suit.  The above is for people who are just starting to figure out their own logistics.

Hi, I am from Quebec. In 2003, my wife and I retired and are living on a campground. After lots of calls, we have a PO box with Canada postal services. The main concern was to give the campground address to the autorities such as Revenue Quebec, Driver's licence autority, provincial medicare and they added a mailing address which is the PO box. For passport, Revenue Canada, Passeport Canada, insurance they only need the PO box number.
Using an address were you are not residing is illegal and with posible consequence such as a fime if stopped by an OPP or any police officer.
Your driver's licence must have your address were you live/reside normaly same for the provincial goverment.

But if you will be living in Mexico more than the legal limit  (210 days in Ontario) then you become a non-resident of Canada and Ontario with the lost of some benefit such as the OHIP but none of pension benefits.

Buena suerte, GyC.

Thank-you GyC.
While we initially are residing in Mexico for less than the 212 day legal limit, going  to help in charity work allows up to 5 years (with their approval) and still keep OHIP.
We have worked out the details for our address now through our legal representative and it will satisfy all government agencies.

Thanks for everyones help......especially Anne S. - that answer helped us the most.

NGPT

May I ask about that place you talked about in Quebec. (Mail service but not a P.O box)
I might need to look them up.
Thank you.

absolutely. here is the link.....
http://www.canadianaddress.ca/

There are others, but I've lost the contact info, and they seemed smaller companies which usually charge more.

Cheers,
NGPT