How to Avoid Spam Filters in Research Text Messages: SMS Delivery Best Practices

Are your research text messages getting blocked or filtered? Mobile carriers use spam filters that can prevent legitimate research messages from reaching participants. This guide covers the most common reasons SMS messages get flagged in research studies and provides practical tips for avoiding content blocks — so your study communications reach every participant.

Optimizing Text Messaging for Research: Navigating Spam Filters

Efficient communication through text messaging has become a cornerstone of modern research studies. However, researchers must now contend with the complexities of mobile carrier spam filters, which can inadvertently block critical study messages.

It’s important to note that mobile carriers decide what constitutes spam. Even with explicit participant consent, research messages are subject to the same filtering standards as any other text. The following guidelines provide strategies to enhance message deliverability and reduce the risk of being flagged as spam. While these tips can improve outcomes, they do not guarantee absolute protection against filtering or number blocking.

Best Practices for Avoiding Spam Filters

1. Make Messages Personal and Conversational Craft messages that feel human and conversational rather than robotic. While it’s unnecessary to include personal health information (PHI), a more natural tone can make messages more engaging and less likely to be flagged.

2. Include Your Organization’s Name Depending on your use case, include the name of your organization or project. This establishes credibility and reassures recipients that the message is legitimate.

3. Avoid ALL CAPS, Special Characters, and Symbols Messages that rely heavily on non-alphanumeric characters or excessive capitalization can trigger spam filters. For example, avoid using ALL CAPS for calls to action or inserting unnecessary symbols like $.

4. Limit Links in Your Messages

   • Use one or two links per message to reduce the likelihood of being flagged.

   • Avoid popular URL shorteners like Bitly or TinyURL, as they are often associated with spam. Mosio’s proprietary link-shortening system is a safer alternative.

   • Avoid sharing unreasonably long or complex links, such as those with excessive parameters or unnecessary data.

5. Send Unique and Varied Messages Repeating identical messages can raise suspicion with mobile carriers. For instance, instead of repeatedly sending “Please take this survey,” provide context or vary the phrasing.

6. Welcome Participants at Enrollment Send an initial welcome message and encourage participants to save your texting number in their contacts. Referencing the project name in this message can also foster trust and engagement.

7. Use Links Thoughtfully Embed links within the context of the message to clarify their purpose. For example: “View the study schedule here: https://example.com/schedule” rather than sending “naked” links.

8. Keep Messages Concise Limit messages to 160 characters or fewer. While longer messages may occasionally be necessary, use them sparingly to maintain clarity and avoid triggering spam filters.

9. Proofread Thoroughly Typos, grammatical errors, and unusual sentence structures can make messages appear suspicious to carriers. Ensure all texts are polished and professional.

10. Provide Opt-Out Options Include an easy way for participants to opt out of messages, such as “Text STOP to unsubscribe.” This not only adheres to TCPA guidelines but also builds trust.

11. Register Your 10-Digit Long Code (10DLC) Mosio simplifies this process for you, ensuring compliance with carrier requirements.

12. Send Messages to Smaller Groups Avoid blasting messages to large lists. Sending texts to smaller groups reduces the likelihood of being flagged as “spammy” bulk messaging.

13. Use Custom Fields for Personalization When sending templated messages, include personalized details to make each message feel unique and authentic. For example, “Hi [First Name], please complete your study survey today.”

Testing and Final Tips

Always test messages before going live. Use multiple phones and carriers to simulate participant experiences and identify any potential issues. Testing can also help ensure that your communications align with your study’s goals and messaging strategy.

By following these practices, researchers can enhance the effectiveness of their text messaging programs, ensuring participants remain engaged and informed throughout the study.

Frequently Asked Questions

Q: Why are my research text messages being blocked?

A: Mobile carriers use automated filters that scan for patterns associated with spam. Common triggers include sending too many messages too quickly, using URL shorteners, including special characters or emojis, and using language that matches SHAFT content categories (Sex, Hate, Alcohol, Firearms, Tobacco).

Q: How can I make sure my research SMS messages are delivered?

A: Use natural language, avoid URL shorteners (use full URLs instead), keep messages concise, include your organization name, collect proper consent, and test messages to yourself before sending to participants. Mosio’s character counter tool can help you optimize message length.

Q: Do spam filters affect text messages for clinical research?

A: Yes. Carrier filters don’t distinguish between marketing messages and research communications. Even well-intentioned study messages can be flagged if they contain certain words, patterns, or formatting that triggers automated filters.

---

Need help ensuring your research messages get delivered? Visit our plans page to learn more or join our virtual office hours to troubleshoot delivery issues with the Mosio team.