SMS and MMS Spam Filtering

Modified on Wed, 05 Jun 2024 at 01:59 PM

Spam filtering for SMS and MMS messages can be managed at telco or device levels. However, SMS messages don't have any indicators that mark them as spam, unlike emails which have various verification systems. 

This guide provides information on how spam filtering is done and steps to prevent your messages from going into spam.


Spam Filtering at Telco Level [AU only]

  • Telcos may filter their messages based on the 'Sender ID' used to send them. For instance, if a user tries to send a message using the Sender ID 'MyGov', the telcos might mark the message as spam and block the send for the messages using that Sender ID.

  • Tall Bob System also applies spam filtering at the Sender ID level. Tall Bob has a default Red List that contains a set of Sender IDs such as MyGov, Medicare, etc. When the user attempts to send a campaign with a Sender ID that is added to the red list, the Tall Bob system marks the messages as 'Undeliverable' hence preventing them from reaching the customers


Filtering at Device Level [IOS and Android]


IOS SMS Filtering:

  • Apple has their SMS filtering enabled by default for all iPhones running iOS 11 or later. Since IOS 11's release in September 2017, Apple has kept the SMS Filter activated by default on all iPhones for a span of over 5 years

Apple's SMS filtering uses machine learning to categorize incoming text messages, helping users identify valid messages and potential spam or promotions. It's important to note that while SMS filtering organizes messages, it doesn't block spam outright.

  • Users also can report a number as spam from their IOS device by simply clicking on the message and selecting the 'Report Junk' option. Click here to learn more about handling Spam and SMS filters in IOS

  • IOS also supports the use of a 3rd party application that can be used exclusively to track spam numbers.

  • In addition to the existing features, iOS 15 has introduced Smart Filtering, which employs machine learning to identify and filter spam messages, including those from contacts.


If the user wants to turn off SMS/Smart Filter, they can do so by navigating to Settings > Messages > Filter Unknown Senders and clicking the toggle to turn off the setting


Android SMS Filtering:

  • If the user has Google Messenger as the SMS handler for their Android device, they benefit from a native filtering option provided by Google. Click here for detailed steps on setting up the Spam filter on an Android device

  • Similar to IOS, Android devices also support the use of a 3rd party application that can be used exclusively to track spam numbers.


Common Contributors to Spam:

  • User reports labelling messages as spam

  • Utilization of generic Sender IDs

  • Lack of clear unsubscribe options

  • Inclusion of multiple links

  • The presence of keywords in the message such as gambling, violence etc.,


How to avoid getting your number marked as spam


Effective Messaging Tactics:

  • Craft concise and informative messages to avoid the appearance of spam.

  • Avoid excessive use of capital letters and exclamation points, as they are common in spam messages.


Sender ID Strategy:

  • Use a Sender ID that users have saved on their phones. This can be achieved through sending MMS messages with vCards for contact saving. Doing this helps the user to Maintain brand consistency and enable two-way messaging with link previews.




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