Why Custom Domains Increase Deliverability and CTR
The domain behind your links does more work than most marketers realize. A generic, shared, or shortened domain doesn't just look less polished, it changes whether your message reaches an inbox or phone at all, and whether the recipient trusts it enough to tap. That's the difference between a link that gets ignored and one that converts: branded, recognizable links see a 34–39% higher click-through rate than generic, shortened ones.
As carriers and mailbox providers tighten filtering in response to a wave of phishing and "smishing" (SMS phishing), the domain you send from has become one of the biggest levers on deliverability and click-through rate (CTR) that marketers control.
The state of the industry
The pressure on generic and shortened links is a direct response to fraud:
Consumers lost $470 million to scams that started with a text message in 2024, more than five times what was lost in 2020 (DeepStrike, 2026).
SMS now accounts for roughly 69% of observed mobile phishing ("mishing") vectors, according to Zimperium telemetry, far ahead of malicious PDFs or QR codes (DeepStrike, 2026).
The Anti-Phishing Working Group has tracked a steady rise in phishing delivered through SMS and social channels quarter over quarter.
Carriers have responded by filtering more aggressively at the network level. That filtering doesn't distinguish well between a scammer's link and a legitimate marketing message using the same kind of shortened, unbranded domain. The result: public URL shorteners and anything that obscures a link's destination are now treated as suspect by default.
What carrier policies actually say
This is written into the rules senders agree to follow. The CTIA's (Cellular Telecommunications Industry Association) Messaging Principles and Best Practices require that any URL shortener have "a web address and IP address(es) dedicated to the exclusive use of the Message Sender." Shared, multi-tenant shortening domains don't meet that bar.
Individual carriers go further in their own codes of conduct:
AT&T: its Code of Conduct for Short Code and 10-Digit A2P SMS Messages states that "the practice of using public URL shorteners in bulk messaging is highly discouraged, and messages containing them may be subject to blocking."
T-Mobile: its Code of Conduct for Messaging uses nearly identical language, plus a clear recommendation that each program use "a single business's web domain," with a branded short URL as the acceptable alternative to a public shortener.
We cover both of these, plus Verizon, in depth later in this series. The throughline: a domain the carrier can tie to your business is safe; a domain shared across thousands of unrelated senders is not.
The deliverability and CTR payoff
The upside is measurable, not just theoretical. Research cited across the link-management industry, including studies referenced by Rebrandly, puts the CTR lift from branded links at roughly 34% over generic short links, with some analyses as high as 39% (U2L, 2026; Messageflow, 2026). Bitly's own research lands in the same range: "short, branded links can boost CTR by up to 34% compared to generic or long URLs" (Bitly, 2026).
The mechanism is simple: when someone can see your brand name in a link before they click, the decision gets easier. An unfamiliar domain adds hesitation, or gets blocked before it's ever seen.
What "custom domain" actually means
The term gets used loosely. It doesn't mean putting your company name somewhere in a URL. It means the domain (or subdomain) is:
Registered to your business
Resolved through DNS records you control
Used exclusively by you, not shared with any other sender
A link like links.yourbrand.com meets that bar, since a carrier can build a reputation history against it over time. A link on a shared platform domain doesn't, even if it includes your brand name in the path, because the underlying domain is still pooled across every other tenant on that platform.
Common mistakes that undercut the benefit
Treating setup as a one-off project. Only a handful of high-value customers get a branded domain; everyone else defaults to shared infrastructure.
Half-finished DNS records. A CNAME pointed at the wrong target or a missing verification record can leave a domain misconfigured, which can perform worse than not attempting it at all.
Inconsistent scope. Setting up a branded domain for email but not SMS, when both channels face the same trust and filtering dynamics.
Why this matters for platforms, not just marketers
This isn't only a marketer's problem. Any SMS or omnichannel platform that lets its customers send messages should be treating a custom domain as a requirement for every customer on it, not an optional upgrade. When a platform doesn't mandate this, its users see worse deliverability and CTR than they would elsewhere, and a platform that's silently costing its customers performance is a platform those customers eventually leave.
How Entri Activate removes the technical barrier closes the gap for customers without a domain
Pointing a subdomain at a messaging platform means creating the right CNAME, TXT, or SPF/DKIM records, and getting that wrong (or skipping it) is one of the most common reasons companies default to a shared domain.
Entri Activate, which includes Entri Connect, turns that multi-step DNS process into a streamlined setup within a few seconds. Instead of looping in an engineer, a customer's marketing team gets a branded, carrier-safe sending domain without building any of that infrastructure themselves.
However, not every customer who needs a branded domain already owns one. "Go buy a domain, then come back and configure it" is a two-step drop-off point.
Entri Sell lets customers purchase a domain directly inside the platform they're already using, in the same flow where they'll connect it. Paired with Entri Connect, that's "no domain" to "fully configured, carrier-compliant domain" without leaving your product.
Together, Connect and Sell create a streamlined motion for users to quickly set up a custom domain. The Entri Unify call entri.showUnify(config) presents a centralized modal where the user chooses to buy a new domain or connect an existing one, then routes them through the right Entri flow automatically. When that flow completes, the domain goes from purchased or owned to fully functional inside your platform and your users can start sending sooner.
See what a branded domain could do for your own deliverability and click-through rate.
Book a Demo and we'll show you Entri Activate running inside a product like yours.