ResenderXiaomi, Redmi, POCO: SMS forwarding stops in the background
Xiaomi's battery manager — MIUI and now HyperOS — is the strictest on Android. Out of the box it stops any app that is not on screen, so an SMS forwarder works while you look at it and goes quiet when you don't. Three settings, set once, fix this for good.
The three settings
- Open the Security app → Permissions → Autostart.
- Find Resender and turn its switch on.
- Then open Settings → Battery → App battery saver → Resender.
- Choose “No restrictions”.
- Autostart. Settings → Apps → Manage apps → Resender: switch Autostart on. Without it, the system does not wake Resender when an SMS arrives after a restart or after the app was stopped.
- App battery saver: No restrictions. On the same screen, open App battery saver and choose No restrictions. The default, Battery saver (recommended), is what delays the forwarding.
- Lock the app in Recents. Open the recent apps view, press and hold the Resender card and tap the padlock. Clearing recent apps then leaves Resender alone.
Then take Resender off Android's own battery optimisation: the app has a button for it on the main screen — it opens the system list, you find Resender and choose Don't optimize. By hand: Settings → Apps → Manage apps → Resender → App battery saver, or Settings → Battery → Battery optimization → All apps.
How to check it worked
Lock the phone, wait a minute, and send it an SMS from another phone. The email should arrive within seconds. If it arrives only after you unlock the phone or open the app, one of the three settings is still off — most often Autostart after a system update.
What no app can do
None of these Xiaomi screens has a public interface. No app can read them, change them, or tell you reliably whether you have set them. Resender shows a red line on its main screen when Android reports that it is being restricted, and opens the right system screen for you — but the switch itself is yours to flip. Skip it, and messages arrive late or not at all while the app has done everything it is allowed to do.
Questions
Messages arrive hours late, or only when I open the app. Why?
MIUI and HyperOS stop apps that are not on screen unless they are allowed to autostart and are excluded from battery saving. Resender receives the SMS only when the system lets it run again — hence the delay. Set the three settings on this page once, and messages go out within seconds.
Why doesn't Resender just switch these settings itself?
Xiaomi's screens have no public interface: no app can read them, change them, or even tell whether you have set them. The one Android setting an app could change with a single dialog needs a permission Google Play grants only to alarms, calling and similar categories, which a message forwarder is not.
I set everything and it still stops after a few days.
Check that Resender is still locked in Recents: clearing recent apps with the broom removes the lock on some versions. Also check that the system has not reset App battery saver after an update — HyperOS updates sometimes do.
Does the phone need to stay unlocked?
No. Locked is fine; off or offline is not. The phone with the SIM must be powered on and have mobile data or Wi-Fi.
Which Xiaomi models does this apply to?
Every phone running MIUI 12 or later or HyperOS: Xiaomi, Redmi and POCO. The names of the menus move a little between versions, but the three settings exist on all of them.