Configuring preferences and options in Outlook.com
To provide the best protection for your account, Safelinks are on by default. You can turn them off by signing in to https://outlook.live.com. Then select Settings > Premium > Security. There's a toggle under Advanced Security that you can use to turn off Safelinks. Note that turning off Safelinks will only affect future messages you receive. It won't change the link format in messages you've already received.