SMS Deliverability Explained: Bot Clicks, Filtering, & Hidden Issues - Klaviyo
2026-03-10 23:08 Diff
https://www.klaviyo.com/blog/sms-delivery

Spam filters used to be something marketers only worried about with email. Now, you need to think about them with SMS, too.

As Apple, Google, and mobile security apps roll out more aggressive protections, many brands are seeing a new kind of issue: messages are marked as delivered by carriers, and analytics show clicks on the links. But some subscribers never see the text at all.

Under the hood, two trends are driving this:

  1. Bot clicks: automated security systems that “click” your links before humans ever see them
  2. Silent suppression: device-level filters that move or hide messages without telling the sender or the carrier

Here, I walk through what’s happening, why your reporting might look confusing, and what you can do to protect your performance.

What’s actually happening when SMS “disappears”?

When you send an SMS campaign, 3 big stages determine whether a subscriber ever sees it:

  1. Carrier delivery: Your message leaves Klaviyo and is handed off to mobile networks. If Klaviyo gets a positive delivery receipt back, we know the carrier accepted and delivered the message to the device.
  2. Device and app filtering: Once the message reaches the phone, things get more opaque. Operating systems and SMS apps can:
    • Route messages to “Unknown senders” or “Spam” folders.
    • Scan content and links before showing the message.
    • Silently suppress or hide messages they deem risky or overly promotional.
  3. Subscriber behavior: Finally, the recipient decides whether to open, click, or reply. This is the only stage you actually want to optimize for, but the two before it are increasingly influential.

The problem is that carriers don’t see what happens at the second stage. If a message is delivered to the device but then silently filtered, the carrier still reports it as delivered, and that’s the information every SMS marketing platform, including Klaviyo, receives.

What are bot clicks?

Bot clicks are automated link visits made by security systems, not by your subscribers.

They typically come from:

  • Mobile OS security features that pre-scan links for phishing and malware
  • Built-in SMS spam protection on Android and iOS
  • Third-party security / antivirus apps on the device or network

Bot clicks exist to keep users safe from phishing, malware, and smishing attacks. They also score URLs and decide whether to show, move, or hide the message. And they can classify future messages from the same sender as safe or risky.

How bot clicks show up in your data

Depending on how your tracking is set up, bot clicks can show up as:

  • Click events with no real human engagement afterward
  • Clicks from a narrow set of IP ranges, often within seconds of send
  • Clicks on profiles that tell you “I never saw that message”

In Klaviyo, these bot-driven link visits are visible at the event level for transparency. They’re not counted in headline SMS campaign performance metrics like click-through rate, so your CTR is based on human behavior, not scanners.

That said, it’s still useful to know which subscribers are having their messages aggressively scanned. More on that later.

What is silent suppression?

Silent suppression is when a message is:

  • Delivered to the device (the carrier says ✅), but
  • Moved out of the primary inbox or hidden entirely by filters, without:
    • A bounce
    • A failure code
    • Any feedback back to the sender

Common patterns we’re seeing:

  • iOS devices moving messages from new, unsaved numbers into an “Unknown senders” or filtered inbox
  • SMS apps (or security tools) flagging certain copy as “too promotional” or “spam-like” and quietly hiding it
  • Android devices with aggressive spam protection enabled, sometimes through third-party apps

Because the suppression happens on the device, after carrier delivery, the carrier reports “delivered” and your SMS platform logs “received,” but the subscriber never actually sees the text.

That’s why your user timeline can show “SMS received” while the subscriber insists they didn’t get anything.

Why silent suppression is suddenly more common

Several trends are converging:

  • iOS and Android are tightening SMS protections, especially for unknown senders.
  • Scams and smishing have exploded, so default spam thresholds are higher.
  • Promotional copy is often indistinguishable from spam at first glance, especially if it leans heavily on:
    • All caps
    • Vague urgency (“Hurry! Don’t miss out!”)
    • Generic links
    • No context or personalization

The good news: brands that adapt their SMS strategy can often cut down on suppression dramatically without sacrificing performance.

How to reduce bot clicks and silent suppression

You can’t fully eliminate security scans or device filters, but you can design your program to work with them instead of against them. Here’s how:

1. Tune your copy to look legit, not spammy

Filters are looking for patterns, not intent. Small changes go a long way.

Avoid overusing

Use instead

  • ALL CAPS SUBJECT-STYLE LINES
  • Multiple exclamation marks!!!!
  • Vague urgency with no time or context
  • Messages that are purely promotional with no explanation
  • Time-anchored context“25% off everything until 11:59 p.m. tonight.” “Your early access code is valid today only.”
  • Blended informational + promotional tone“Your early Black Friday access code is LIVE: BF25. It gives you 25% off everything until midnight.”
  • Conversational, human language“Hi [first name], your early access to our Black Friday sale just opened. Use code BF25 for 25% off until midnight.”
  • Mixed case or lower case instead of shouting“25% off everything” instead of “25% OFF EVERYTHING”

Think: “important notification with an offer” rather than “billboard condensed into 160 characters.”

2. Make it easier for phones to trust your messages

Technical and structural choices also influence filtering. Here’s what to keep in mind:

  • Use verified / branded sender IDs or short codes. Messages that clearly show your brand name feel safer and are more recognisable.
  • Prefer branded short links over generic public shorteners. Public shorteners are heavily abused by spammers and are more likely to be scrutinised.
  • Limit the number of links. One clean, branded link per SMS is typically best.
  • Be consistent with your sending domain. If the domain in your SMS is the same one subscribers see in your emails and on your site, it reinforces trust.

3. Build a test panel of “canary” subscribers

Because phone behavior is a black box, test groups are your best friend.

Create a small, controlled segment of internal team members or trusted customers who:

  • Use a mix of iOS and Android.
  • Use different carriers.
  • Have a mix of security settings (spam filters on/off, etc.).

Before major campaigns:

  1. Send them the exact message you plan to send your broader audience.
  2. Ask them to check:
    • Primary SMS inbox
    • Unknown sender / filtered tabs
    • Spam / junk folders in their messaging apps
  3. Adjust copy if:
    • Delivered status is ✅ but the message is hidden/suppressed.
    • Certain devices consistently don’t show the campaign.

This won’t give you a perfect delivery rate for your whole list, but it will give you early warning when the filters don’t like your content.

4. Segment and adapt for “high-risk” profiles

Over time, you’ll notice patterns, like some profiles showing bot clicks frequently, some consistently not engaging much with text messages, and some complaining that they’re not seeing your messages, even though delivery is “successful.”

Treat these profiles as high-risk for suppression and adjust your strategy by:

  • Sending them simpler, more transactional-style messages
    • “Your access code is BF25, valid today until 23:59.”
    • “Your Cyber Monday offer: 80% off sale items until midnight.”
  • Reducing “shouty” creative and vague urgency
  • Considering re-engagement or confirmation flows to re-establish trust

You can still market to these people. You just need to get past the bouncers first.

5. Measure success beyond raw delivery

Given the growing gap between “delivered” and “actually seen,” the most actionable KPIs are:

  • Click-through rate (human-only)
  • Conversions and revenue per recipient
  • Unsubscribe rate
  • Engagement by segment / cohort

In Klaviyo, bot clicks are visible in events, so you can diagnose issues. But, headline CTR excludes bot activity, so you’re looking at real people, not scanners.

At the campaign level, think in terms of: “Did this message drive meaningful actions?”, not “Did 100% of devices choose to surface this content?”

6. Start planning for richer, more trusted channels (like RCS)

As we outlined in our iOS 26 update, the future of mobile messaging is moving toward rich, verified, interactive formats like RCS.

Benefits include:

  • Branded sender with logo and name
  • Rich layouts that feel more like mini landing pages
  • Additional signals of authenticity that spam filters can use

RCS won’t replace SMS overnight, but it’s worth:

  • Identifying high-impact use cases (product drops, promos, back-in-stock)
  • Talking with your CSM about RCS beta access and roadmap
  • Designing campaigns that can work in both SMS and rich formats

Can you ever know exactly how many messages were suppressed?

Short answer: no, and that’s true for every provider in the market.

This is because carriers only know whether a message was delivered to the device. Device filters and security apps don’t report back when they hide or move a message. That suppression happens locally, on the phone, after delivery is confirmed.

What you can know:

  • How many messages your carriers accepted and delivered.
  • How many human recipients clicked and converted.
  • How different segments (and test panels) behave with different content.

That’s why the following are now core parts of a modern SMS strategy:

  • Testing with a known panel
  • Segmenting based on behavior and bot activity
  • Iterating on copy and structure

Turning bot clicks and filters into a competitive advantage

Silent suppression and bot clicks can feel scary, especially in peak season. But they’re also a forcing function.

They push brands to:

  • Write clearer, more intentional SMS copy.
  • Treat subscribers like people, not just phone numbers.
  • Integrate SMS into a broader, trust-based, omnichannel experience.

At Klaviyo, we’re working closely with carriers and partners to keep you informed as filters evolve. We’re also investing in richer messaging channels like RCS and surfacing the right data so you can see enough to make good decisions, even when phones don’t tell us the full story.

If you’re seeing confusing gaps, “delivered” but not seen, or strange click patterns, talk to your CSM or our support team. We can help you:

  • Audit your recent sends.
  • Identify likely suppression patterns.
  • Design test flows and segments to improve inbox placement.

The rules of SMS are changing. Brands that adapt early, by blending smart copy, thoughtful testing, and rich messaging, will be the ones that keep their messages where they belong: in front of their customers.