How to Set Up a Google App Password for Email Warmup

If you're warming up your email through CampaignStack (or any other third-party service), Google won't let you connect with your regular password. You need an App Password, a one-time 16-character code that lets CampaignStack send and receive emails on your behalf.

The whole thing takes about two minutes.

Prerequisites

Before you start, you need 2-Step Verification turned on. App Passwords don't exist without it: Google only shows the option once 2FA is active.

If you haven't enabled 2FA yet:

1. Go to myaccount.google.com/security
2. Under "How you sign in to Google", click 2-Step Verification
3. Follow the prompts to add a phone number or authenticator app
4. Once verified, come back here

Already have 2FA on? Skip ahead.

Step 1: Open the App Passwords page

Go directly to myaccount.google.com/apppasswords.

Google may ask you to re-enter your password. That's normal.

Can't find the page? The App Passwords option only appears when 2-Step Verification is enabled. If you see an error or the page doesn't load, go back to the prerequisites above.

Step 2: Create an App Password

On the App Passwords page:

1. In the "App name" field, type something you'll recognize later, such as CampaignStack
2. Click Create

Google generates a 16-character password displayed in a yellow box. It looks like this:

abcd efgh ijkl mnop

Copy this password now. Google only shows it once. If you close the window before copying, you'll need to generate a new one, which is fine: you can create as many as you need and revoke old ones.

Step 3: Paste it into CampaignStack

Back in CampaignStack:

1. Open the Warmup tab in your workspace
2. Click the email account you want to warm up
3. When prompted for an App Password, paste the 16-character code you just copied
4. Click Connect & start

CampaignStack validates the password immediately. If the connection succeeds, warmup begins within minutes.

What does this actually do?

An App Password lets CampaignStack send and receive warmup emails through your Gmail account using SMTP/IMAP. It's the same way Outlook, Thunderbird, or Apple Mail connect to Gmail.

Unlike OAuth ("Sign in with Google"), App Passwords can be revoked one by one without touching your main Google password. Delete the App Password, and CampaignStack loses access immediately.

Troubleshooting

"The option doesn't show up" You need 2-Step Verification enabled first. See the prerequisites section above.

"Password was rejected" Make sure you copied all 16 characters, including spaces. The most common mistake is missing the last group. Also verify you're using the App Password, not your regular Google password.

"I closed the window before copying" No problem. Go back to myaccount.google.com/apppasswords, delete the one you created, and generate a new one.

"I want to revoke access later" Visit the same App Passwords page and click the trash icon next to the entry you created. Access is cut immediately.

Google Workspace accounts

If your email is managed by an organization (Google Workspace, formerly G Suite), two things are worth knowing before you ask your admin for anything.

Do not ask for "less secure app access". You will find that phrase in a lot of older guides. It no longer exists. Google finished retiring it for Workspace accounts on May 1, 2025, and removed the setting from the Admin console entirely, so an admin cannot turn it back on even if they want to. Signing in to IMAP, POP or SMTP with a plain username and password stopped working at the same time.

App Passwords survived that change and are still the supported path for a device or service that cannot do OAuth. What your admin actually controls is one step upstream:

• 2-Step Verification has to be allowed for your account. No 2SV, no App Passwords page. This is an Admin console policy, and it is the usual reason the page returns an error for a work address that works fine on a personal one.
• IMAP access has to be on for your user. Admins can turn POP and IMAP off per organizational unit, and when it is off a perfectly valid App Password still fails to connect.

If your organization enforces OAuth only and will not budge, write to support@campaignstack.io and we will work out an alternative.