Why do some messages return a "soft bounce" message status? – Sinch

A soft bounce indicates that a message could not be delivered due to a temporary issue, but may be successfully delivered if retried. Soft bounces don’t mean failure — they highlight temporary issues that you can manage to improve your campaign delivery.

This is different from a hard bounce, which indicates a permanent delivery failures, where the message cannot be delivered at all.

Monitoring and managing bounces helps improve deliverability and campaign performance.

Soft bounce vs hard bounce

The table below explains the key differences between soft and hard bounces.

Type	What it means	Typical causes	What you should do
Soft bounce	Temporary delivery issue — message may be delivered later	Phone switched off, network issue, inbox full, carrier delay	Retry sending later
Hard bounce	Permanent delivery failure — message cannot be delivered	Invalid number, deactivated number, blocked recipient	Remove or correct the phone number

Key differences

Soft bounce = temporary issue ✅
Hard bounce = permanent issue ❌

Common causes of soft bounces

Soft bounces typically occur due to temporary conditions on the recipient’s side or within the network:

Device-related issues	The recipient’s phone is switched off The device is out of coverage. Action: Retry sending later.
Network or connectivity issues	Temporary network disruptions Poor signal or connectivity Action: Retry sending later.
Device or storage limitations	The recipient’s device cannot receive new messages (e.g. storage full). Action: Retry or follow up with the user if the issue persists.
Carrier or routing issues	Temporary operator or routing problems. Action: Retry sending after some time.

What should you do when you see soft bounces?

To manage soft bounces effectively:

Retry sending the message after a short delay
Monitor recurring soft bounces on the same numbers
Investigate patterns (e.g. country, operator, campaign timing).

Best practices

If a number repeatedly returns soft bounces over time, it may indicate a deeper issue and should be reviewed.

Why soft bounces matter

Soft bounces are an important indicator of delivery quality. They help you:

Understand temporary delivery issues
Monitor the real reach of your campaigns
Optimise campaign performance over time.

Related to