How to improve SMS deliverability

Text messages get opened within minutes. For marketers, that immediacy is the whole point—but only when messages actually arrive.

SMS deliverability is the metric on which everything else is built. Strong copy, well-timed sends, and compelling offers don't convert if carriers filter your messages before they reach the audience you worked hard to build. This guide covers what affects your delivery rate, how to improve it, and why link security is one of the most overlooked factors in the equation.

‍

What is SMS deliverability?

SSMS deliverability is the percentage of text messages that successfully reach recipients' devices, versus those that are blocked, filtered, or rejected by carriers. It's often used interchangeably with SMS delivery rate, and it answers a fundamental question: Did your message actually make it through?

Deliverability isn't the same as open rate or response rate. Subscribers can still ignore a message after it arrives. But a message that's blocked never has a chance to perform.

Poor deliverability wastes your budget and skews your campaign data. A drop from 98% to 90% delivery might seem small, but across one million messages, that’s 80,000 people who never received your text—and 80,000 messages you paid for that accomplished nothing.

Industry benchmarks suggest aiming for 95% or higher delivery rates. Anything consistently below that signals problems with your compliance, content, infrastructure, or sender reputation.

How to calculate and track SMS delivery rate

The SMS delivery rate formula is straightforward:

Delivery Rate = (Messages Delivered ÷ Messages Sent) × 100

If your platform shows 48,500 delivered messages out of 50,000 sent, your deliverability rate is 97%.

Most SMS platforms provide delivery receipts with status codes that show what happened to each message:

Delivered: The recipient’s device received the message Failed: The message couldn’t be delivered due to invalid numbers, carrier rejection, or technical issues
Pending/Unknown: The carrier hasn’t confirmed delivery yet

Single delivery reports are useful, but tracking rates across campaigns, carriers, and regions gives you better insights. A drop in one region might signal local filtering rules. A sudden decline across all campaigns could indicate sender reputation problems.

What affects SMS deliverability rates?

SMS delivery isn't guaranteed. Every message passes through carrier filtering systems designed to protect users from spam, fraud, and malicious content. Understanding what triggers those filters is the first step to improving your results.

Carrier filtering and spam detection

Mobile carriers actively scan SMS traffic for suspicious patterns. Their goal is to stop phishing, malware, and fraud before messages reach consumers. Spam filters evaluate sender behavior, message content, and historical performance—and they act automatically.

Carriers flag signals such as:

• Sudden spikes in sending volume
• Repetitive or template-heavy content
• High complaint or opt-out rates
• Links associated with phishing or malware

Link security is a particular concern. Carriers scan URLs inside messages, and a link pointing to a domain with a history of abuse—or one that looks unverifiable—can get a message blocked before it ever reaches a recipient.

Sender reputation factors

SMS sender reputation is built over time and determines how carriers treat your messages. Carriers track past behavior to decide whether to deliver, throttle, or block your traffic.

Key contributors include:

• 10DLC registration and compliance for application-to-person (A2P) messaging
• Sender ID authentication
• Complaint and opt-out rates
• Consistency in sending patterns
• Historical campaign performance

Link reputation is part of that equation. Carriers don't just evaluate your phone number or sender ID—they also track the domains included in your messages and how those links have performed historically across different recipients and devices.

Technical compliance requirements

Carriers expect brands to meet regulatory and technical standards consistently—and will penalize those that don't. Non-compliance isn't just a legal risk; it's a direct deliverability risk.

Core requirements include:

• TCPA compliance
• Clear opt-in and opt-out mechanisms
• Message content restrictions
• Avoidance of prohibited content categories

Campaigns that fall short of these standards are far more likely to be throttled or blocked.

List quality and hygiene

The quality of your contact list has a direct impact on deliverability. Outdated numbers, recycled phone numbers, and disengaged recipients all increase complaints and failed deliveries.

Poor list hygiene leads to:

• High bounce rates from invalid or recycled numbers
• Higher complaint rates from uninterested recipients
• Patterns that signal to carriers your program lacks proper consent

Carriers read all of these as signs of low-quality traffic, which puts your future delivery rates at risk.

How to improve SMS deliverability

Deliverability improves when carriers trust you—and trust is built through consistent, compliant behavior over time. The practices below address the most common causes of filtering and blocking.

Get proper opt-ins and consent

Poor opt-in practices are one of the most common causes of deliverability problems. Carriers monitor how you build your list and how subscribers interact with messages—and that data influences how they treat your traffic.

Use double opt-in to confirm intent, clearly explain what subscribers will receive, and make your brand identity explicit at the point of sign-up. Keep records of consent; if complaints arise, documentation matters for both compliance and sender reputation. Transparent opt-in practices reduce unsubscribes and complaints, which protects your delivery rate over time.

Register your sending numbers properly

For application-to-person (A2P) messaging in the U.S., 10DLC registration is required. Registering your brand and use case tells carriers who you are, what you're sending, and what volume to expect—making it far less likely that your traffic gets flagged.

The process includes brand registration, campaign vetting, and choosing a sending method. Short codes offer higher throughput and built-in carrier trust. Long codes, when properly registered, provide more flexibility and scale for many organizations. Aligning your 10DLC registration with your actual sending behavior is what keeps carriers from throttling or blocking your traffic.

Maintain clean contact lists

List hygiene has a measurable impact on deliverability. Sending to invalid, inactive, or recycled numbers raises your bounce rate and signals poor data quality to carriers.

Remove hard bounces immediately, suppress inactive subscribers, validate numbers before any new campaign launch, and set a regular schedule for list cleaning. The result: fewer wasted sends, better engagement rates, and a healthier sender reputation.

Follow carrier guidelines for content

Message content affects deliverability more than most marketers expect. Carrier filters analyze your messages for patterns associated with fraud, deception, or misleading behavior—not just known spam.

Avoid excessive capitalization, aggressive punctuation, and spam trigger phrases. Be especially careful with prohibited content categories like gambling and alcohol, which are high-risk even when sent to opted-in subscribers. Clear, direct messaging that aligns with your registered use case is less likely to trigger filtering.

Prioritize link security in every message

Links are one of the most overlooked deliverability risks. Carriers actively scan URLs inside messages, and the trust signals your links send—or fail to send—often determine whether a message is delivered or filtered.

Generic link shorteners rely on shared domains that bad actors routinely abuse. Even well-run campaigns can get caught in that association—carriers may flag a message not because of what you sent, but because of what someone else sent from the same domain. Unclear ownership and prior abuse history make those links far more likely to trigger filtering.

Rebrandly gives your links the trust signals carriers look for. Every link includes HTTPS encryption, is backed by SOC 2 Type 2 compliance, and can be configured with password protection, expiration controls, and access restrictions. Those features make your links easier to verify—and your messages easier to deliver.

Monitor and manage sender reputation

Track delivery rate trends, complaint and opt-out rates, sending volume, and engagement patterns—catching issues early matters because many deliverability problems compound over time. Keep an eye on post-click behavior too; sudden spikes or unusual activity can trigger carrier filtering if left unaddressed.

Measuring and tracking SMS deliverability

Make sure you have a strategy in place to assess your campaigns and improve deliverability continually.

Key metrics to monitor

A strong deliverability strategy looks beyond a single metric. Delivery rate and carrier benchmarks provide a baseline view of your SMS delivery rate. In contrast, bounce rates—especially your SMS bounce rate split between hard and soft bounces—indicate list health.

‍

Opt-out and complaint rates reveal how recipients perceive your messages, and response rate serves as a useful engagement indicator. Link click-through rate is another important signal; low engagement can suggest trust or relevance issues that negatively affect deliverability over time.

Tools and platforms for tracking

Most SMS platforms provide analytics dashboards that track delivery, bounces, and opt-outs. Carrier feedback loops and third-party deliverability monitoring tools add deeper visibility into SMS spam filters and blocking behavior. Rebrandly Analytics adds another layer by tracking link performance and identifying link-related delivery issues on top of your SMS marketing analytics.

When to investigate deliverability issues

Certain patterns should trigger immediate investigation. Sudden drops in delivery rates, carrier-specific blocking, or campaigns where messages with links fail while plain-text messages succeed are all warning signs. Link-related filtering remains one of the most common and least obvious causes of SMS delivery problems.

Common SMS deliverability problems and solutions

Here are four common SMS deliverability issues you can encounter, and how they impact your overall campaign performance.

High bounce rates

Outdated lists, invalid or recycled numbers, or weak opt-in practices often cause high bounce rates. A rising SMS bounce rate can quickly damage sender reputation. Preventing these issues starts with validating numbers at collection, cleaning lists regularly, and removing hard bounces as soon as they occur.

Carrier blocking due to security concerns

Carrier blocking often stems from trust issues related to the link. Generic shorteners with shared abuse histories and unrecognized domains are common triggers. Carriers identify these issues when messages containing links fail while text-only messages succeed.

The most effective resolution is to switch to branded, verified domains and to strengthen SMS link security over time. Rebrandly’s security features help prevent these blocks before they impact campaigns.

Low engagement impacting reputation

Engagement acts as a feedback signal for carriers. When recipients consistently ignore messages, it suggests poor relevance or trust. Improving engagement through better segmentation, timely messaging, and aligned use cases helps protect SMS sender reputation.

Compliance violations

Common SMS compliance mistakes include missing opt-out language, sending outside approved use cases, or incomplete 10DLC registration. Regular program audits help identify these issues early. Correcting them quickly is critical for restoring carrier trust and protecting long-term deliverability.

Use SMS deliverability as a competitive advantage

SMS deliverability determines whether your strategy actually reaches people. Strong campaigns fail when messages don't arrive—and the gap between a message that gets delivered and one that gets blocked is often smaller than marketers expect.

Compliance, list quality, and sender reputation are well-understood factors. Link security less so. But carriers scan every URL in every message, and the trust signals your links carry—or fail to carry—are often the difference between a delivered message and a filtered one.

Rebrandly gives SMS marketers and platform teams the link infrastructure to improve deliverability at scale: branded domains, HTTPS encryption, SOC 2 Type 2 compliance, and Rebrandly Analytics to surface link-related issues before they compound.

Ready to see how it works for your program? Book a demo with our team.

‍