The From address says your store. The link the customer clicks says bit.ly, or a tracking host shared by thousands of other accounts. Those are different names, and filters are allowed to care about both. Authentication of the message does not vouch for every hostname in the HTML.
Neither Gmail nor Yahoo publishes any rule, quota, or penalty for URL shorteners. That is not a clearance: gateways and filters judge link hosts by their own reputation data, which is why the advice below is labeled as practice rather than requirement.
Last verified: 26 September 2026. Gmail and Yahoo do not publish a numeric “shortener penalty.” The guidance below is labeled so it stays that way.
Three different hostnames
| Hostname | What it is | What it is not |
|---|---|---|
| From domain | The brand in the visible address. Needs SPF, DKIM, and DMARC. | The click-tracking host |
| Mailed-by / return path | Often the ESP, unless you configured a custom one. See why the mailed-by domain matters. | Proof the links are yours |
| Tracking or shortener host | Where the href goes before the store | A substitute for authentication |
Link density measured how many links were in the message. It did not measure whether those links were on a public shortener. Do not quote that study as a shortener result. Content versus reputation keeps the content studies in their own lane.
Public URL shorteners in email
A public shortener is shared infrastructure. You do not control who else uses it, and you often do not control how long the redirect lives. Receivers and corporate gateways have a long history of treating well-known shorteners as higher risk because the destination is hidden and the domain’s reputation is shared. That history is industry practice and gateway behavior. It is not a line in Google’s bulk-sender requirements.
Recommended practice for your store: put clicks on a hostname you own. If a partner insists on their shortener, that partner’s domain is now part of your message’s URL reputation for that send. One partner link is not a crisis. A whole campaign of them is an avoidable dependency.
Branded tracking domains
Klaviyo and most ESPs will CNAME a subdomain such as click.yourstore.com to their tracker. The customer sees your name. The ESP still records the click. This is worth doing because the hostname matches the brand and you can remove it if you leave the ESP.
It does not replace the sending domain. A perfect tracking CNAME with broken DKIM alignment still fails DMARC. Set up the From domain in Klaviyo’s custom sending domain or the equivalent at the other ESP, and use subdomain strategy if receipts and marketing should not share a name.
A link that 404s, or a tracking host that no longer resolves, is a broken experience and sometimes a broken hostname. It is not, by itself, a Gmail spam-rate rule. Google’s formatting guidelines say links in the body should be visible and easy to understand, so the recipient knows what a click will do. A dead href fails that guideline. Fix the URL. Do not expect the spam-rate chart to be the tool that reports a 404.
When you change ESPs, the CNAME has to move or mail will send with broken or foreign links. The migration guide should include that DNS cutover. A tracking host left pointed at the old vendor is how “we authenticated the new ESP” still produces dead links and a hostname you no longer intend to use.
Redirects
One hop through your tracking host to the product page is ordinary. The risk shows up when the chain is shortener, then affiliate network, then another shortener, then the store. Each hop is another domain a gateway can dislike, and another place the destination can change after you send.
Recommended practice: one branded hop, then your site. Do not claim a provider will spam-folder you at three hops. If placement dropped in the same hour you changed link domains, check the new host with the email blacklist checker (what a listing means) and compare placement before and after. The drop might be the domain. It might be the audience you mailed that day. The provider split tells you whether every inbox moved or only one did.
InboxEagle
Check your tracking domain against blocklists
The free blacklist checker looks up a domain or IP on the major blocklists. Run it on your click host and any shortener you plan to use, then check placement at Gmail, Yahoo, AOL and Outlook after the change.
Sources
- Email sender guidelines, Google. Authentication and a consistent sending identity. No published shortener quota.
- Sender best practices, Yahoo. Authentication and complaint rate for bulk senders. No published hop-count rule.
- RFC 7208 and RFC 9989 cover SPF and DMARC for the sending identity, not the reputation of a third-party shortener.