Deliverability Check

You already know that there are federal and state (or provincial) laws regulating texting that you must comply with, not to mention the CTIA Messaging Principles and Best Practices imposed by the various carriers. You're ready to send a message that complies with all of those, but now you're wondering if there's anything else you should think about that could impact deliverability.

When composing a Broadcast message, the platform will analyze your message for content known to lead to deliverability issues such as carrier filtering. The platform will also help to flag best practices. In most cases, the algorithm used by carriers is not published and is constantly evolving. Our deliverability check will evolve as best practices and new markers for potential issues become available.

Note that we will not programmatically restrict the ability to actually send the broadcast, even when red-flag warnings are surfaced. Ultimately, the messages you send are completely in your control and compliance is your responsibility.

Deliverability checks for Personalization, Flagged Content, Links, MMS Size, Message Length, and Compliance wording will be displayed in one of three states:

No potential issue detected.

An issue exists that is known to have the potential to cause deliverability issues.

An issue exists that will almost definitely lead to deliverability issues.

Even if no potential issues are detected, we cannot guarantee delivery of texts. Carriers can block any message at any time without warning or explanation.


Personalized messages lead to the highest engagement as well as the highest deliverability. Consider using field merge to personalize each outbound text.

Note that in cases where field merge is used and there is missing data associated with contacts to be texted, a warning will be surfaced letting you know that an incomplete field merge may result.

Flagged Content

T-Mobile has indicated that they will start levying penalties for traffic that is offside their Code of Conduct. This would include SHAFT (Sex, Hate, Alcohol, Firearms, Tobacco) violations, spam, phishing, and messaging that meets the Severity 0 violation threshold per the CTIA Short Code Monitoring Handbook.

It should therefore come as no surprise that some keywords will lead to aggressive carrier filtering (across the board):

We have seen some less aggressive filtering on the following keywords, which we will surface as a warning:

Additionally, when messages contain multiple capitalized keywords, carrier filtering can be triggered.


Sending Links in your messages can lead to aggressive carrier filtering. Specifically, use of public link shorteners such as can lead to very quick blocking. Utilizing a smart link can alleviate issues with public link shorteners.

Carriers are also looking for https:// and http:// in your messages. When these are present, reduced deliverabiliity may result. Note that this check in particular seems carrier dependent and isn't as much of an issue with some carriers.

Parameterized links (for instance or very long links (greater than 35 characters) are likely to be heavily carrier filtered.

MMS Size

Videos that are larger than 500kb will be flagged. In addition, images greater than 1mb may experience deliverability issues.

Images larger than 2 MB can’t be delivered as MMS and will be delivered as a link.

Images larger than 1 MB may experience deliverability issues.

Video files larger than 500 KB experience very severe deliverability issues and may be delivered as a link instead of native video.

Message Length

Very long messages may lead to substantial costs as well as deliverability issues — carriers have been known to block very long messages more aggressively.

Use of Emoji and Unicode characters in a message will decrease the segment character count from 160 characters to 53. We flag the characters that lead to the smaller segment size.


In some use cases, adding a "Reply STOP to opt out" at the end of your text may increase deliverability.

Effect of 10DLC Registration and Toll-Free White Listing on Carrier Filtering

Getting 10DLC registered does not preclude all carrier filtering. While the effects of registration and toll-free whitelisting are yet to be fully known, we believe the carriers will still flag inappropriate keywords, long parameterized links, and the use of link shorteners.