# MCPmailer vs ImprovMX

ImprovMX forwards mail on your domain to a mailbox you already read. MCPmailer is the mailbox an agent holds the conversation in.

Also searched as: ImprovMX alternative, email forwarding for AI agents, ImprovMX for agents.

## What ImprovMX is

ImprovMX forwards mail addressed to your domain into a mailbox you already have, free for basic use, with paid plans from a few dollars a month and a small SMTP add-on if you also need to send. It is simple, fast, and does exactly one thing.

## Where ImprovMX is the better choice

If you want support@yourdomain.com to land in an inbox you already read, ImprovMX is the cheapest and least fussy way to do it. For a solo founder or a small alias set, it is the right tool.

## Where MCPmailer differs

Forwarding is a delivery mechanism, not a mailbox. Nothing is stored, so there is nothing to search, no thread to continue, and no history for the agent to read. Add a send path and you own DKIM alignment, bounces, and suppression too.

### Nothing is stored, so nothing can be read back

A forwarder passes the message on and forgets it. An agent that needs to know what it told this person in March has to have kept the mail somewhere, which is exactly what the mailbox, the thread model, and search_inbox are for.

### Forwarding is where DKIM goes to die

Forwarded mail is often modified in transit, which invalidates the original DKIM signature and can fail DMARC alignment with it. Mail delivered to its own mailbox on your verified subdomain has no intermediate hop to break.

### Sending is a separate purchase and a separate problem

The SMTP add-on lets you send, and then bounce handling, complaint feedback, suppression, and reply-first quotas are yours. Those are the controls that keep a sending domain alive once an agent is choosing recipients.

## When forwarding is enough

Be honest about which of these describes your case.

1. **An alias a human reads** Forwarding is correct and nearly free. Nothing here improves on it.
2. **An agent that must reply in thread** It needs stored mail and a thread model, which a forwarder does not have.
3. **Both, briefly** Forward a legacy alias into an agent address while you cut over, then drop the forward.

## Side by side (checked July 2026)

| | MCPmailer | ImprovMX |
| --- | --- | --- |
| Built for | Agents holding conversations. The mailbox is the product, not an endpoint bolted onto a sender. | Forwarding addresses on your domain to an existing mailbox. |
| Inbox per agent | One mailbox per agent, created from the dashboard or the API, each with its own scoped key. | Aliases, not mailboxes. |
| Receiving and threading | The mailbox is the destination, not a hop. Mail is stored, threaded, and searchable where it lands. | Forwarded onward. Nothing is retained. |
| MCP server | Native. Streamable HTTP with a bearer key, or OAuth 2.1 for clients that cannot hold one. | No. |
| Waiting for a reply | wait_for_reply long-polls the mailbox until the other side answers, up to five minutes per call. | No. |
| Human oversight | Every thread is readable in your dashboard and you can take any of them over yourself. | Forwarding logs. |
| Sending limits | Reply-first. Replies into an inbound thread are near-unrestricted; cold outreach is quota gated. | Sending belongs to the SMTP add-on or your own provider. |
| Your domain | Instant you.mcpmailer.email subdomain, then verify agents.yourcompany.com with a guided DNS wizard. | Your own domain, with their MX records. |
| Search | Full-text search over mail the workspace actually holds, rather than over whatever the destination kept. | None. Whatever the destination mailbox kept. |
| Beyond the inbox | A shared contact book with per-contact memory, notes, an encrypted vault, and a public hostname per agent. | Nothing beyond aliases. |
| Free tier | 3,000 emails a month, 100 a day, 3 inboxes, no card. | Free for basic forwarding. |
| Content privacy | We never read message content and never train on it. Enforcement is behavioral and metadata only. | Mail passes through in transit. |

## Questions

### Can I use ImprovMX to give an agent an address?

You can give it an address that forwards somewhere. The agent still needs a mailbox to read from, a way to send, and somewhere the thread lives.

### Does forwarding hurt deliverability?

It can. Forwarding often modifies the message and breaks the original DKIM signature, and once DKIM fails DMARC alignment can fail with it.

### Is MCPmailer more expensive?

Yes, and it should be: forwarding stores nothing, and most of what you are paying us for is what happens after the mail arrives.

### Can I forward an old alias into an agent inbox?

Yes, and it is a good way to migrate. Keep the forward until in-flight threads dry up, then remove it.

All comparisons: https://mcpmailer.com/vs
Docs: https://mcpmailer.com/docs.md
Pricing: https://mcpmailer.com/pricing.md