Sending accounts are used to create automatic tests and email tests via proxy email addresses. You can use the SMTP settings of most popular mailbox providers such as Gmail, Google Workspace, Outlook, and Office 365 and the SMTP settings of email service providers and delivery services that allow to use their SMTP servers in third party applications.
Below are the steps to create a sending account with the Outlook SMTP settings:
In your account, go to Inbox Insight -> Sending Accounts.
Click Create Sending Account and enter the information:
Sending account name: any name that you want to appear in the From field if your emails
From email: your email address set up with Outlook.com
SMTP server: smtp-mail.outlook.com
Port: 587
SMTP username: your email address set up with Outlook.com
SMTP password: the App password created in your email account set up with Outlook.com.

Important: To create an App password, you need Two-Step Verification on your Outlook.com account to be turned On.
Sign-in to your My Microsoft Account homepage.
Go to Security and click Advanced Security Options.
In Additional Security, click to turn the two-step verification to On if it’s Off.
Follow the steps to enable the two-step verification.
When you are asked to set up the Microsoft Authenticator, click Cancel to go to the next step.
After a few screens, you’ll return to the one where you first enabled 2FA, and there you can choose Create a new app password.

Copy the generated App Password and then click Done.
Paste the App password in the SMTP Password field in the sending account settings.
You may want to save this App password to a safe place in order you can use it again in the future. If you lose your App password, you can always create a new one following the above steps.
Choose a folder to create tests made via this sending account in.
Select the spam filters and email providers to be used for the tests made via this sending account.
Click Check & Create.