Microsoft is offering free Xbox Live credit to select users that can range from $5 to as high as $10. It can be redeemed by accessing the code given in an email.
To gain access to such promotions and enjoy free code, you will have to activate the option to get product offers and other updates in an email from Xbox Live Store. Once you have activated it. you should be able to get the gift codes that are usually sent ahead of a big sale. Xbox Live is currently offering a huge sale on more than 500 games in the lead up to Black Friday.
The email is easy to check because it says in the title “Free gift card-just for you!” and the code given can be redeemed to avail $5 to $10 in Xbox Live credit. For some users, Microsoft is even offering 1 month of Xbox Live Game Pass, although you can purchase it for yourself by using the current promotion which offers 1 month of Xbox Live Game Pass for $1 only.
As for how to check if you are eligible for this promotion, there is, unfortunately, no way. Just like Sony, Microsoft picks up the people who are given the gift card randomly. If they have pre-defined criteria for it, they have never made it clear.