Anyway, how are you managing mail in your mac after forwarding it to another email provider? I think that setting the outlook (in my case) account also on my mac might be the best idea... does anyone has a better idea?
I think the easiest way to do it is a clean break - i.e. setup gmail's forwarding so that it deletes every email after it forwards it on to the outlook.com account.
You can also migrate your entire gmail account, folders and mails, etc. over to outlook.com first when you do this so that you just have gmail as a "proxy" if you will, so you don't have to ever go in there again and just start using the outlook.com account as primary.
In fact, the easiest way to do this migration is to skip the whole set up to send from the gmail.com account. You will still get all the emails that people send to your old email account, and you will have all the old emails migrated over to the outlook account, so you won't miss anyting at all, and people will eventually just start replying to you outlook address, and even if they don't, it will be seamless to them and to you, nobody will miss anything...
Follow this guide if you want to cut your google cord.
http://www.pcworld.com/article/2011519/how-to-move-from-gmail-to-outlook-com.html
I might just do this myself for my private accounts. We use Google Apps for business for work, and it is good value for money, but they have devalued their free services to the point of forcing one away unless you are willing to use their app offerings exclusively. Fair play to them for trying to go more vertical and lock people into an ecosystem (sound familiar?) but that actually goes against what drew me and most early adopters to them in the first place, which was supposed to be free and great services for all (albeit where you are the product, not the customer). Now they want to monetise both sides of their business, and make money from both the product itself (its users) and their customers (the corporate marketing machines that purchase the rights to know everything about all of us google users) and that seems to be getting a tad greedy for me.