Email Blocklist
Always Block Known Spam Senders & Domains
Create an email blocklist to always block specific senders or domains. Email Ferret blocklist ensures known spam senders, unwanted vendors, or specific domains are never allowed through, even if they pass spam detection.
How Does Email Blocklist Work?
Always Block
Blocklisted senders or domains are always blocked, regardless of spam scoring. This ensures known spam senders are never allowed through.
Domain or Address
Block individual email addresses or entire domains. Domain-level blocks are more powerful but should be used carefully to avoid blocking legitimate emails.
Immediate Effect
Blocklist entries take effect immediately and apply to all future emails from those senders. You can add or remove entries at any time.
Why a Blocklist Alone Won't Stop Cold Email
A blocklist is a list of identities, and the economics of cold outreach are built to make identity cheap. A sales team running an automated sequence does not send from one domain until it burns out. It registers a batch of lookalike domains, warms each one for a few weeks so it accrues a clean sending reputation, rotates through them, and retires each before enough recipients report it.
So blocking is inherently retrospective. Every entry you add is a record of mail that already reached you, and the next message arrives from acme-outreach-4.com instead of acme-outreach-3.com. You can keep adding entries forever and never get ahead, because you are always one domain behind a system that generates them faster than you can list them.
What does not rotate is behavior. A first-contact message with sales framing, a call to action, template-shaped personalization, and a follow-up scheduled four days out looks the same from every domain it is sent from — because those traits are what make the campaign work. Email Ferret scores that behavior, which is why it catches the fifth domain without ever having seen the first four.
The blocklist earns its place as the manual override on top of that: for the senders you want stopped as a matter of policy, not probability.
How to Build a Blocklist That Holds Up
Four steps, and the fourth is the one most people skip.
Find a sender worth blocking
Open your flagged mail and look for names that keep coming back. A single unwanted email is not worth a blocklist entry — the scoring already handles it. What earns an entry is the sender you have now seen four times this month under four different subject lines.
Decide between the address and the domain
Block the address when one person is the problem and the company is not. Block the domain when the company is the problem — when blocking one rep just means the next rep on the team picks up the sequence a week later. Sales teams rotate senders, so domain-level is usually the entry that actually holds.
Add the entry
Add it from the Email Ferret dashboard, or straight from a flagged message without switching tabs. Entries take effect on the next message that arrives; there is no sync delay to wait out.
Check it caught the right thing
After a domain block, search Gmail for that domain once. This is the step people skip, and it is the one that catches the mistake worth catching — a shared platform domain, or a company you buy from as well as get pitched by.
Blocklist, Allowlist, or Scoring — Which One to Reach For
| Situation | Use | Why |
|---|---|---|
| The same agency has pitched you five times | Blocklist the domain | A known repeat sender is a policy decision, not a judgment call worth re-scoring every time. |
| A recruiter you actually want to hear from keeps getting flagged | Allowlist the address | Their mail is textbook cold outreach. The allowlist is how you tell the scoring that this particular stranger is welcome. |
| Unfamiliar sales mail from domains you have never seen | Leave it to scoring | This is the majority of cold outreach, and it is exactly the case a blocklist cannot cover — you cannot list a domain before it exists. |
| A newsletter you signed up for and stopped reading | Unsubscribe first | Legitimate senders honor unsubscribe. Save blocklist entries for the ones that don't. |
Before You Block a Whole Domain
Domain-level blocking is the strongest entry you can add, and the one most likely to catch something you wanted. Three cases are worth checking first:
- Shared sending platforms. Some domains carry mail for thousands of unrelated businesses. Blocking one takes out every sender behind it, including ones you have never heard of and might want.
- Vendors you also buy from. A company whose sales team pitches you may be the same company that sends your receipts, password resets, and support replies. Block the rep, not the domain.
- Large employers. One persistent SDR at a company of ten thousand people is not a reason to silence the other 9,999 — one of whom may be interviewing you next year.
None of this is irreversible: blocked mail is labeled, not deleted, and removing an entry restores normal scoring immediately. But finding out a month later that you missed something is worth one Gmail search now.
Frequently Asked Questions About Email Blocklist
Learn how to create and manage an email blocklist
Create Your Email Blocklist
Never receive emails from known spam senders. Email Ferret blocklist ensures unwanted senders and domains are always blocked. Try it free—no credit card required.
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