Please follow the below mentioned steps to add a Yahoo account in Canary for macOS:
1) Open Canary.
2) In the system menu bar, open the Canary Mail menu.
3) Click on Add Account.
4) Click on Yahoo.
5) Enter your Yahoo e-mail address. Doing so will open Yahoo’s authentication page so you can sign into your Yahoo account.
6) Click Next.
7) Enter your Yahoo password.
8) Then, click on the blue ‘Agree’ button to grant Canary Mail access to your email account, so you can use your Yahoo within Canary.
9) When redirected back to Canary, enter an arbitrary Account Name. This is how Canary will identify the account.
10) Enter your Name, as you would like message recipients to see it in your messages’ From field.
11) Click continue.
