At Kudosity, we understand how frustrating it can be when SMS messages appear to be delivered but never actually reach the recipient’s attention. One of the most common reasons for this is Android’s built-in spam filter—an invisible yet powerful barrier to effective communication.
What’s happening?
Many businesses rely on SMS for critical notifications, confirmations, and marketing messages. However, Android devices automatically apply a spam filter that is controlled by Google, not mobile carriers or messaging providers.
The key issue? Messages are successfully delivered to an Android handset, with a positive Delivery Receipt (DLR) confirming the delivery—but the Android system may suppress the notification or move the message to a spam folder. This means recipients never see the message, even though it was technically delivered.
What we know
Google, not carriers, controls the spam filter. There’s no official guidance on what triggers filtering, making it difficult to predict or prevent.
Delivery Receipts confirm delivery to the handset. However, this does not guarantee visibility.
It affects all sender types. While virtual numbers (DVNs) are impacted more often, even Alphanumeric Sender IDs can be caught in the filter.
Changing sender ID formatting (e.g. capitalisation) doesn’t help. If ‘ABC COMPANY’ is filtered, ‘abc company’ will likely be as well.
It’s not just marketing messages. Transactional messages—like booking confirmations or verification codes—can also be hidden.
What can you do?
While neither aggregators nor carriers can override Google’s filtering rules, there are a few best practices that may improve message visibility:
Use different Sender IDs for important notifications. If a particular sender ID is being filtered, using an alternative (where possible) could improve visibility.
Encourage recipients to check their spam folders and mark your messages as ‘Not Spam’ to improve future delivery.
Consider a multi-channel approach. For mission-critical messages, SMS should be supported by alternative channels such as app-based notifications.
The bottom line
SMS remains a powerful tool, but Android’s spam filter introduces an unpredictable challenge. While messages are reaching devices, their visibility is ultimately in Google’s hands. By staying informed and applying best practices, businesses can maximise their chances of successful message delivery.
If you’re facing visibility issues, get in touch with our team—we’re here to help.
