When you click Test connection or send, SheetCourier says:
Google refused the password. Use an app password (a special 16-letter password Google gives you for apps), not your normal Gmail password. No app password yet? Turn on 2-Step Verification first, then create one.

Why it happens #
Google does not let apps sign in with your normal Gmail password. Mail servers report this as error 535. SheetCourier needs an app password instead.
Fix it #
- Make sure 2-Step Verification is on for your Google account: 2-Step Verification.
- Create an app password named SheetCourier: App passwords. Copy the 16 letters.
- In SheetCourier, open Email accounts, click Edit on the Gmail account and paste the app password into App password. Spaces don’t matter.
- Click Test again, then Save changes.
The full steps with screenshots are in Connect Gmail.
Still refused? #
- Check that Your email address is the Gmail address the app password belongs to.
- Did you change your Google password? Google then deletes all app passwords. Create a new one.
- “Google blocked this sign-in”: 2-Step Verification is off. Turn it on, then create a new app password.
- Can’t find App passwords at all? See App passwords option is missing.
- Google Workspace account: if your Google account is managed by your work or school, your admin may have turned off app passwords.
