How to Block an Email Sender (and Allow Trusted Ones)

Sometimes you don’t want to shut down a whole alias — you just want to block an email sender who’s become a nuisance, while everything else on that alias keeps working. EmailAlias lets you do exactly that: silence one specific sender (or an entire domain) across your account, so their messages are quietly dropped before they reach you. This guide shows how to block an email sender, how the matching allowlist lets your trusted contacts always get through, and how blocking a sender differs from disabling an alias — so you reach for the right tool each time.

What Blocking a Sender Does

Blocking a sender tells EmailAlias to refuse mail from that address — or that whole domain — before it’s forwarded to you. The message is dropped silently: it never lands in your inbox, and the sender receives no bounce, no error, and no hint that they’ve been blocked. From their side the email looks delivered; on your side it simply never arrives.

That silent drop is deliberate. A bounce message would tell a spammer your address is live and being actively managed, which invites more spam. By dropping quietly, blocking closes the door without ringing a bell. It’s a precise tool — you’re removing one specific sender, not touching the alias itself, so every other message to that alias keeps flowing normally. This kind of targeted email filtering is exactly what you want when a single contact turns sour.

How to Block an Email Sender

There are two easy ways to block an email sender, depending on where you’re starting from.

From a message that already reached you. This is the quickest:

1. Open your logs. Go to the activity view where your forwarded messages are listed.
2. Find the message from the sender you want gone. Each forwarded email shows who sent it.
3. Click Block. A single click adds that sender’s domain to your blocklist. From then on, mail from that domain is dropped before it reaches you, and the message row shows it’s now blocked.

By adding an entry directly. If you already know the address or domain you want to stop:

1. Open the Spam filters page in your dashboard, which has an Allowlist panel and a Blocklist panel.
2. Add to the Blocklist. Type a full email address (to block one specific sender) or a bare domain (to block everyone at that domain), and add it.
3. Done. Any future mail matching that entry is dropped silently. You can remove the entry at any time to un-block.

Blocking a whole domain is the heavier hammer — useful when an entire service or a spammy marketing platform is the problem — while blocking a single address surgically removes just one correspondent. You can keep up to a large number of entries, so your blocklist can grow as needed. If you’d rather stop all mail to a given address instead of one sender, that’s a job for disabling the alias — more on that difference below.

The Allowlist: Always Let Trusted Senders Through

Blocking has a mirror image: the allowlist. Where the blocklist stops specific senders, the allowlist guarantees specific senders always get through. Add a trusted address or domain to your allowlist and its mail bypasses the spam filter entirely — it’s always forwarded, never held back or marked, no matter what.

This solves the opposite problem to spam: important mail being caught by mistake. If a bank, a client, or a service you rely on ever risks being filtered — because their messages look unusual, or come from a domain with a mixed reputation — allowlisting them makes sure their mail reaches you every time. It’s the safety valve that lets aggressive spam filtering stay aggressive without ever costing you a message that matters. Together, the allowlist and blocklist give you a simple rule for both ends: this sender always in, that sender always out.

Block a Sender vs Disable an Alias

Blocking a sender and disabling an alias both stop unwanted mail, but they work at different levels. Choosing the right one keeps your setup tidy.

The rule of thumb: if an alias is still useful but one sender on it is a nuisance, block that sender. If the whole address has leaked or you’re finished with it, disable the alias. For example, if a shop you still want emails from gets bought by a spammy marketer who starts blasting you, block that marketer’s domain and keep the alias. But if an alias you gave one shop starts getting mail from dozens of strangers, the address itself has leaked — disable it.

What Happens to Blocked Mail

When a blocked sender emails you, the message is stopped at the door and dropped — it isn’t forwarded, isn’t stored for you to read, and doesn’t generate a bounce message back to the sender. The only trace is a line in your activity log noting that a message was blocked and why, so you can see the filter working and reverse it if you ever change your mind.

This “silent drop” behaviour is the same approach serious anti-spam techniques use, and it’s on your side: spammers learn nothing, legitimate senders you’ve blocked by choice simply stop reaching you, and you keep a record either way. It’s worth knowing that some senders are also blocked automatically — for instance, if you ever mark a forwarded message as spam through your own mail provider, or a domain floods you, EmailAlias can add it to your block list for you, so the worst offenders are handled without you lifting a finger.

When to Block an Email Sender (and the Scope)

Reach for the blocklist whenever a specific sender is the problem rather than the address itself:

• A persistent spammer who keeps emailing one of your aliases despite the alias still being useful for other mail.
• A marketing platform that a company you deal with uses to blast you — block the platform’s domain and keep the company’s real messages.
• A single bad actor — one address sending you unwanted mail that you want gone without disrupting anyone else.

One important detail to understand: your allow and block lists are account-wide, not tied to a single alias. When you block a sender, they’re blocked from reaching any of your aliases, and an allowlisted sender is trusted across all of them. This is usually exactly what you want — if a sender is a spammer, you don’t want them getting in through a different alias — but it’s worth knowing, so you don’t expect a block to apply to just one address. If you genuinely need per-address control, that’s where separate aliases and the disable switch come in, working alongside your global block and allow lists as covered in our guide on how to stop spam emails.

Plan and Limits

A few practicalities:

• Allow and block lists are a Premium feature. Managing your own trusted and blocked senders is part of Premium ($4/month). The automatic spam filtering that protects every account runs for free users too; the manual lists are the paid control on top.
• You can add plenty of entries. Each list holds a generous number of addresses or domains, so you can build up a substantial blocklist over time without running out of room.
• Entries can be an address or a domain. Block or allow a single email address for precision, or a whole domain to cover everyone who sends from it.
• It’s always reversible. Remove an entry from either list at any time, and the sender is treated normally again from that point.

Tips for Allow and Block Lists

• Block the domain when a whole service is the problem; block a single address when it’s just one person. Match the tool to the size of the nuisance.
• Allowlist your most important senders early — your bank, your main clients — so a stray spam filter can never hold up mail you truly need.
• Use blocking before deleting an alias. If only one sender is bothering you, block them and keep the alias; don’t throw away a useful address over a single nuisance.
• Review your lists occasionally. A quick look now and then lets you remove entries you no longer need and confirm your allowlist still reflects who matters.
• Combine with per-service aliases. Blocking handles individual bad senders; giving each service its own alias handles leaks and lets you disable a whole address when needed. The two work best together.

How Blocking Fits Your Wider Setup

Blocking senders is one tool in a small kit that works best together. The foundation is using an email alias for each service, so every stream of mail is separate and traceable in the first place. When you create an alias per signup, a spam problem is already narrowed to one relationship — and from there your allow and block lists give you the fine control to trust or stop individual senders across everything.

These lists also complement the automatic defences running in the background. If an address you gave one company suddenly attracts mail from strangers, that’s a leak, and EmailAlias’s leak detection can flag it — at which point disabling the alias is the right move, not blocking each new sender one by one. The blocklist is for when a specific, known sender is the nuisance; the alias off switch is for when the address itself has gone bad. Think of the allowlist as a personal whitelist that guarantees your important contacts, the blocklist as your personal deny list, and per-service aliases as the structure that makes both precise. Used together, they cover every case: trust this sender always, stop that one everywhere, and shut down a whole address when it leaks — with no collateral damage to the rest of your mail.

Final Thoughts

Being able to block an email sender gives you a scalpel to go with the alias’s off switch. When a whole address has served its purpose or leaked, you disable the alias; but when just one sender turns into a nuisance on an address you still want, you block that sender and keep everything else. Their mail vanishes quietly, they’re none the wiser, and the rest of your inbox is untouched — and the matching allowlist makes sure the senders you care about are never caught by mistake. Next time one bad correspondent starts cluttering an alias you rely on, don’t bin the whole address: block the sender, and carry on.

Frequently Asked Questions