Steam allows you to generate Backup Steam Guard Codes. These codes are very useful to have when you don't have the access to your mobile authenticator or email. You can generate these codes only when you have steam guard, and mobile authenticator enabled. In order to generate Backup codes, you will need to have both steam guard, and mobile authenticator enabled.
The interesting part is that when you are logging into your account using one of the generated backup codes, you won't have the full access to your account, meaning that you cannot change anything. This is especially a great opportunity to make boosting services even safer. By entering your account with the pre-generated code, the booster won't be able to do anything with your account and only have access to the games, which is the only thing required for completing an order.
Here is a guide on how to generate the backup codes:
Open Steam desktop app or visit Steam website in your browser and find settings button.
In the top right corner, click on account name, and select the account details tab.
Click on Manage Steam Guard as shown on the screenshot below.
Click on Get Backup Guard Codes button.
SMS will be sent to your linked mobile phone, enter the code in the field and click confirm.
Once everything is completed, you will see a list with 30 generated backup codes, each code can only be used once.
We kindly ask our customers to provide these codes since this can significantly improve the working process, and there will be no need for us to wait for the customer's reply to log in into their account. Booster will proceed to work right away within the agreed hours.