Add Yahoo Mail to Roost: app password, step by step

Before you start

Your Yahoo address and password, to sign in on Yahoo’s page.
The browser you normally use for Yahoo Mail, not a private window. Yahoo only offers app passwords in a browser you’ve signed in with for several days in a row.
Roost open on Add your inboxes, with your address typed in.

You make the app password on login.yahoo.com, Yahoo’s own site. Roost never sees your Yahoo password.
Roost keeps the app password in your Mac’s Keychain and has no server to copy it to.
You can delete it on Yahoo’s page at any time, and Roost loses access at once.

Open Yahoo’s Account Security page

Click Yahoo Account Security in Roost’s setup line, or go to login.yahoo.com/myaccount/security in the browser you use for Yahoo Mail. Sign in if Yahoo asks.
Click Create app password

It’s under External connections.

A simplified drawing of Yahoo’s page, with Yahoo’s words.
Type “Roost” and click Generate password

The name is only a label for you.

Check the address bar says login.yahoo.com.
Copy the password, then click Done

Copy the code Yahoo shows (⌘ C). No need to write it down: if you lose it, make a new one.

A made-up example. Yours will be different.
Paste it into Roost and click Connect

Paste it in App password and press Return.

This is Roost.

There’s no Create app password button: Yahoo decides who may make one. Its help says to use a browser you’ve signed in to Yahoo with for several days in a row, and not a private window. If you just set up this Mac, keep using Yahoo Mail in Safari for a few days, then try again. Yahoo’s customer care can’t switch it on for you.
Roost says Yahoo needs an app password, not your usual one.: You typed your Yahoo password. Make an app password (steps 1 to 4) and paste that.
Roost says That password didn’t work.: A character was probably lost on the way. Make a new one and paste it instead of typing.
Yahoo asks you something when you sign in on the web: Answer it first. Yahoo says to deal with any sign-in question on its website before signing in from an app.

Is this my Yahoo password?

No. It’s a separate code Yahoo makes for one app. Your normal Yahoo password doesn’t change.

Do I need two-step verification?

Yahoo’s help doesn’t require it for app passwords. It’s still a good idea for your account.

What if I change my Yahoo password?

Your app password keeps working. Yahoo only stops it when you delete it.

Can Roost see anything besides my mail?

Roost only connects to Yahoo’s mail servers (imap.mail.yahoo.com and smtp.mail.yahoo.com). Everything Roost talks to is on Where your mail goes.

How do I remove Roost’s access later?

In Roost: Settings, pick the inbox, Remove Inbox…. At Yahoo: Account Security, External connections, your app passwords, then Delete next to Roost.