SMS Deliverability: Ensuring Your Nonprofit's Texts Arrive

What is SMS deliverability?

SMS deliverability is the rate at which your text messages successfully reach recipients' phones. Unlike email — where messages can land in spam folders and still technically be "delivered" — an undelivered text simply doesn't arrive. The supporter never sees it.

For nonprofits running time-sensitive campaigns like Giving Tuesday appeals or disaster response, deliverability is the difference between a campaign that raises money and one that reaches nobody.

Understanding deliverability is especially important given the scale of the U.S. messaging ecosystem. According to CTIA's annual survey, Americans send and receive trillions of text messages each year, and carriers have built increasingly sophisticated filtering systems to manage that volume. Nonprofit organizations must understand how these systems work to ensure their fundraising and engagement messages reach supporters reliably.

What affects SMS deliverability

Sender type and registration

The type of number you send from directly affects deliverability. Dedicated short codes have the highest throughput and deliverability because they're pre-vetted by carriers. 10DLC (10-digit long code) numbers require registration with The Campaign Registry (TCR) and offer good deliverability for registered campaigns. Unregistered numbers face aggressive filtering and throttling.

The distinction between sender types matters more than many nonprofits realize. Short codes are provisioned through a multi-month vetting process where carriers review your use case, message templates, and compliance practices before approving. This vetting process is precisely why short codes enjoy preferred deliverability status — they represent verified, trusted senders. Long codes (standard 10-digit phone numbers), by contrast, were originally designed for person-to-person communication and have been repurposed for application-to-person (A2P) messaging, which is why they require 10DLC registration to achieve acceptable deliverability.

Carrier filtering

Mobile carriers (AT&T, T-Mobile, Verizon) actively filter messages they consider spam or non-compliant. The CTIA Messaging Principles and Best Practices outline the industry standards that govern carrier filtering. Filters evaluate message content, sending patterns, sender reputation, and opt-out compliance. Messages flagged by filters are silently dropped — you won't get a bounce notification.

Each major carrier operates its own filtering infrastructure independently. T-Mobile uses a system that evaluates messages in real time against known spam patterns and maintains a reputation score for each sending number. AT&T and Verizon employ similar but distinct filtering engines. Because each carrier filters independently, a message might be delivered on one network but blocked on another — making it difficult to diagnose issues without per-carrier delivery reporting.

Carrier filtering has grown substantially more aggressive in recent years. In response to rising volumes of robotexts and scam messages, carriers have invested heavily in machine learning models that analyze message content, URL patterns, and sending behavior. The FCC has encouraged carriers to take a proactive approach to blocking unwanted messages, which means even legitimate senders can be caught in filters if they exhibit patterns associated with spam.

Content triggers

Certain content patterns trigger carrier filtering:

• Public URL shorteners — Generic shorteners (bit.ly, tinyurl) are heavily filtered because spammers use them. Use your platform's branded short links instead.
• Excessive capitalization and special characters — ALL CAPS and strings of exclamation marks look like spam to carrier filters.
• Prohibited content — Carriers block content related to certain regulated industries. Nonprofit messaging is generally low-risk, but political messaging may face additional scrutiny.
• Multiple links per message — Stick to one link per text. Multiple links increase filtering risk.
• Identical message content at scale — Sending the exact same message body to thousands of recipients in a short window can trigger pattern-matching filters. Personalizing messages with the recipient's name, giving history, or other unique elements helps each message appear organic rather than mass-produced.
• Embedded phone numbers — Including a phone number within the body of a text message (especially a different number from the sender) can trigger filters designed to catch callback scams.

Opt-out compliance

Carriers require — per FCC rules under the TCPA — that every SMS program honor STOP requests immediately and automatically. If your platform doesn't process opt-outs correctly, carriers can suspend your sending privileges entirely. This is both a TCPA compliance requirement and a deliverability requirement.

Beyond the legal mandate, opt-out handling directly affects your sender reputation. When supporters text STOP and continue receiving messages, they may file complaints directly with their carrier. Carriers track complaint rates per sending number, and high complaint rates lead to throttling, filtering, or outright suspension. Best practice is to confirm opt-outs with a single acknowledgment message ("You've been unsubscribed. Reply START to re-subscribe.") and suppress the number from all future sends immediately.

Sending volume and patterns

Sudden spikes in sending volume — going from 1,000 messages a month to 100,000 in a single day — can trigger carrier rate limiting. Warm up new numbers gradually, and use a platform with carrier-grade throughput designed for high-volume sending.

Volume warming is a critical concept that many organizations overlook. When you provision a new sending number, carriers have no history on that number and default to cautious filtering. Best practice is to start with a few hundred messages per day and increase volume by 20-30% each day over the course of two to three weeks, building a positive sending history before ramping to full campaign volume. This is especially important for 10DLC numbers, which have lower initial throughput limits than short codes.

Sender reputation

Carriers maintain a sender reputation score for each sending number, similar to how email providers maintain IP reputation. Your reputation is influenced by multiple factors: opt-out rates, complaint rates, the ratio of delivered-to-filtered messages, how often recipients engage with your messages, and whether you've had previous compliance violations.

A strong sender reputation is built over time through consistent, compliant sending practices. Once damaged, reputation can take weeks or months to rebuild. This is one reason why using a dedicated sending number — rather than a shared one — is so important for nonprofits. With a shared number, another organization's poor practices can damage the reputation that your messages rely on.

10DLC registration: a step-by-step overview

For nonprofits using 10-digit long codes instead of short codes, 10DLC registration is now required by all major U.S. carriers. The process involves two layers of registration:

1. Brand registration: You register your organization's identity with The Campaign Registry (TCR), providing your organization's legal name, EIN, address, and website. Nonprofits with verified 501(c)(3) status typically receive higher trust scores, which translates to better throughput and deliverability.
2. Campaign registration: You register each distinct messaging use case (fundraising, event notifications, advocacy alerts, etc.) with a description of the campaign, sample messages, and confirmation of opt-in practices. Each campaign receives a trust score that determines your message throughput.

After registration, carriers assign throughput limits based on your trust score. Higher-trust campaigns can send more messages per second. Nonprofits generally score well because the nonprofit use case is considered low-risk by carriers, but the registration must still be completed to avoid filtering. Your messaging platform should handle the registration process on your behalf — at momoGood, we manage the entire registration workflow for our customers.

How to improve nonprofit SMS deliverability

Use a dedicated short code

A dedicated short code is the gold standard for nonprofit SMS deliverability. It's registered, pre-approved by carriers, and can send thousands of messages per second without throttling. Shared short codes carry risk — if another organization on the same code violates compliance, your campaigns can be disrupted.

Register your 10DLC campaigns

If you use a 10-digit number instead of a short code, register it through The Campaign Registry. Registration tells carriers your traffic is legitimate and significantly improves deliverability compared to unregistered sending.

Maintain clean subscriber lists

Remove invalid numbers, honor opt-outs, and regularly clean your list of unengaged subscribers. Sending to invalid or opted-out numbers hurts your sender reputation and increases filtering. A good cadence is to review list hygiene quarterly: remove numbers that have been unreachable for 90+ days, re-confirm consent for subscribers who haven't engaged in six months, and ensure your import process validates phone number formats before adding them to your list.

Use your platform's link tools

Use your messaging platform's built-in link shortener instead of public URL shorteners. Platform-native links use trusted domains that carriers recognize, improving both deliverability and click tracking.

Write natural, clear messages

Avoid spammy language patterns. Write texts that sound like they're from a real organization to a real person. Include your organization name, a clear purpose, and a single call to action. Personalize where possible — a message that says "Hi Sarah, your $50 gift was matched!" reads very differently to carrier filters than an identical blast sent to 100,000 numbers.

Monitor deliverability metrics

Your messaging platform should report delivery rates per campaign. If delivery rates drop below 95%, investigate immediately — it usually means a content or compliance issue is triggering carrier filtering.

Look beyond aggregate delivery rates and monitor per-carrier performance. A 96% overall delivery rate might mask a situation where you have 99% delivery on two carriers and 85% on a third — indicating a carrier-specific filtering issue that needs targeted attention. Real-time monitoring is especially important during high-volume campaigns like Giving Tuesday, where a filtering issue in the first hour can be corrected before it affects the rest of the send.