Address limits

Every address starts with no limits of its own, and the plan of the workspace is the only cap until somebody sets one. Limits sit on top of the plan, so a message has to pass both. They hold on every way mail leaves the address: the app, the assistant, the API and the SDKs, MCP, mail apps over SMTP, sign-up forms, broadcasts, automations and booking pages. Receiving limits hold on mail that arrives here, which leaves out connected mailboxes, as Receiving explains.

An address an AI agent works from is the usual case. Allowed recipients set to client.com, a cap of 50 messages a day and allowed senders set to client.com mean the agent only writes to that client, never more than 50 times a day, and only hears from them.

• —An hour is the current clock hour in UTC, so it starts again on the hour.
• —A day is the last 24 clock hours, the current one included, so it lets go of one hour at a time.
• —A month is the calendar month in UTC.

A storage quota caps how much mail one address keeps. It is set in bytes, from 1 MiB (1,048,576) to 1 TiB (1,099,511,627,776), and the limits of the address report what it keeps now as usage.storage, with its bytes and its messages.

• —Each message the address receives counts once it is filed in its mailbox, at the size it arrived, together with its original when the address keeps originals. A plus tag counts toward the address it belongs to.
• —Counting began when storage quotas shipped. Mail an address held before then is not counted, so its total can be lower than what its mailbox holds.
• —Mail routed to a webhook is never stored in a mailbox, so it never counts. Sent copies, drafts and messages a mail app uploads do not count either.
• —Deleting mail for good makes room again: deleting a conversation forever, emptying the Bin, and the retention of temporary mail. Moving a conversation to the Bin keeps it, so it still counts.
• —Removing a domain stops counting what its addresses kept. Their conversations stay in the mailbox but no longer count toward any quota.
• —Moving a domain to another workspace takes what its addresses keep with it, and so does renaming the free address that follows a username.
• —In the web app, the Storage quota field sits in the Receiving section of the Limits tab, in megabytes or gigabytes, and the Usage section shows the stored mail with its number of messages. In the phone app, the Limits tab of the address screen sets the storage quota too.

Allowed recipients, blocked recipients and allowed senders each hold up to 100 entries, and case does not matter:

• —[email protected] matches that address alone.
• —client.com matches every address at that domain, and not at its subdomains.
• —*.client.com matches every subdomain of it, such as mail.client.com. Add client.com as well to include the domain itself.

A mail app that sends over SMTP gets the same answers as SMTP replies: 451 4.7.1 while sending is paused or a cap is used up, so the app tries again later, 550 5.7.1 when sending is disabled or a recipient is not allowed, and 452 4.5.3 for too many recipients. In the app, the composer says why the message was stopped.

• —A message counts when it is accepted, so a scheduled message counts the moment it is scheduled. A message a limit refuses counts for nothing.
• —Recipients count every address in to, cc and bcc. A plus tag counts toward the address it belongs to.
• —Received mail counts once it is filed. Mail that is turned away does not count.
• —Usage is counted for every address, limited or not, so a new cap starts from what the address has already sent or received in that window.
• —Sends made with a test API key are never limited or counted.
• —Forwarding stays apart: mail an address forwards to other places does not count toward its sending caps and is not held by a sending hold. Mail the address turns away is never forwarded.
• —Counting started when address limits shipped, so nothing sent or received before then is in the totals. Stored mail is counted from when storage quotas shipped.
• —The limits of an address come with its usage for the current hour, the last 24 hours and the month, with the mail it keeps in usage.storage, and with resets: when the hour starts again, when the oldest counted hour drops out of the last 24, and when the month starts again.

• —Reading the limits of an address needs domains:read, and changing them needs domains:write.
• —Changing them also needs reach of the address: the workspace owner, or a member whose role reaches it. Anyone else gets 403 insufficient_authority.
• —An API key or a connected app limited to some addresses only reaches the limits of those, and any other address answers 404.
• —A mailbox login can read the limits of its own address and cannot change them.
• —Moving a domain to another workspace takes the limits of its addresses with it, and what they keep.

• —In the web app, on the Limits tab of the address page, under Settings → Addresses. In the phone app, on the Limits tab of the address screen.
• —Over REST, GET and PATCH /domains/{id}/addresses/{addressId}/limits. The patch takes sending and receiving: a field left out stays as it is, null clears it, and clearing every field brings the address back to no limits.
• —In the SDKs, domains.getAddressLimits(id, addressId) and domains.updateAddressLimits(id, addressId, patch), under the same names in Python, Ruby, PHP, Go, Java and C#, written the way each language writes names.
• —On the command line, nextmail domains get-address-limits and nextmail domains update-address-limits.
• —Over MCP and in the assistant, getAddressLimits and setAddressLimits. setAddressLimits changes what an address may do, so it asks before it runs, and whoAmI lists up to 20 addresses that have limits of their own.

nextmail domains update-address-limits <domain-id> <address-id> --sending-per-day 50 --sending-allowed-recipients client.com --receiving-allowed-senders client.comnextmail domains update-address-limits <domain-id> <address-id> --receiving-storage-bytes 1073741824nextmail domains get-address-limits <domain-id> <address-id>