How to Sign Your Android App (.aab) and Publish It to Google Play

When you generate an Android app from Rebrand → Generate Apps in your dashboard, Mailbux builds a branded Android App Bundle (an .aab file) and gives you a download link. The .aab is the modern publishing format Google Play expects — you do not upload an .apk to the store anymore. This guide takes you from that downloaded file to a live listing on Google Play.

What you'll need

• The .aab file you downloaded from the rebrand dashboard.
• A Google Play Developer account (one-time $25 registration at play.google.com/console).
• About 30 minutes for the first submission. Google review usually takes a few hours to a couple of days.

Step 1 — Create the app in Play Console

1. Sign in to the Google Play Console and click Create app.
2. Set the app name (your brand), default language, and choose App and Free (or Paid).
3. Accept the declarations and create the app.

Step 2 — Let Google manage signing (recommended)

An app on Google Play must be cryptographically signed. The simplest, safest path is Play App Signing: Google holds the secure "app signing key" and you keep an "upload key". Because the .aab we generate is already prepared as an upload artifact, you usually do not have to create or manage a keystore yourself.

1. Go to Release → Setup → App integrity.
2. Ensure Play App Signing is enabled (it is on by default for new apps).

Keep your upload key safe. If your build uses a custom upload keystore, store the keystore file and its passwords in a password manager. Losing it means you can't ship updates under the same listing.

Step 3 — Upload the .aab

1. Open Release → Testing → Internal testing (best for your first upload) and click Create new release.
2. Drag your .aab into the App bundles area.
3. Add release notes and click Next → Save.

Internal testing lets you install the real, store-delivered build on your own devices within minutes — verify branding, login, and push notifications before going public.

Step 4 — Complete the store listing

Google won't let you publish until the listing is complete. Fill in:

• Main store listing — short & full description, app icon (512×512), feature graphic (1024×500), and at least 2 phone screenshots.
• App content — privacy policy URL, data-safety form, target audience, ads declaration.
• Store settings — category (Productivity / Communication works well for an email app) and contact details.

Step 5 — Promote to production

1. When testing looks good, open Release → Production → Create new release.
2. Reuse the bundle from testing (or upload the same .aab), set the rollout countries, and submit for review.

Shipping updates later

Whenever you change branding or a new app version is available, regenerate the Android app from the rebrand dashboard, download the new .aab, bump nothing manually, and upload it as a new release. Play App Signing handles the rest.

Troubleshooting

• "You uploaded an APK or Android App Bundle that was signed in debug mode." Regenerate the app from the dashboard and upload the fresh .aab — debug artifacts are never produced by a normal generate.
• "Version code already used." You already uploaded this build; regenerate to get a new version, or upload to a different track.
• Upload key mismatch. Use the same Play Console app you first uploaded to; don't create a second app for the same brand.

Next in the series: ship the same brand on Apple devices → Sign & publish your iOS app (.xcarchive), or get it onto computers → Distribute your branded desktop app.