Terms of Service | Mailcycle

1. Who these terms are between

These Terms of Service (the “Terms”) are an agreement between Northlab Studios Ltd, a company registered in England and Wales with company number 17462734, whose registered office is at 167-169 Great Portland Street, London W1W 5PF, United Kingdom (“Mailcycle”, “we”, “us”), and the person or organisation that creates an account (“you”, “Customer”).

If you are agreeing to these Terms on behalf of an organisation, you confirm that you have authority to bind that organisation, and “you” means that organisation.

These Terms incorporate our Acceptable Use Policy and our Refund Policy. Our Privacy Policy explains how we handle personal data as a controller; it is information for you and is not part of this contract. Where you are a data controller and we process personal data on your behalf, our Data Processing Agreement also applies and takes precedence over these Terms on data protection matters.

2. The service

Mailcycle provides hosted email infrastructure that allows you to create inbound email addresses and assign them to devices (“Workers”) that you pair with your account, including AI agents: software you run that reads and sends mail through the mailcycle-mcp MCP server (“Agents”). The service includes the web application, the iOS and Android applications, the API, the MCP server and the client libraries (SDKs) we publish (together, the “Service”).

Mailcycle receives mail addressed to your email addresses and makes it available to you and to the devices and Agents you have assigned. The free tier receives mail only. On paid plans you can also send mail from those addresses, within hourly limits and a daily limit set by your plan. On plans that include them, the API and Agents can send too, Agents from the addresses assigned to them, within their own hourly limit and the send mode you set for each. Incoming messages larger than 25 MB are refused. Mail you send can carry up to 10 files, 3.5 MB between them, and program and script files are refused.

We may change, add or remove features. Where a change materially reduces core functionality you rely on, we will give you at least 30 days' notice as section 17 describes. You may then end these Terms under section 12 without penalty, and section 7 says what we refund.

3. Your account

You are responsible for:

The accuracy of the information you give us.
Keeping your recovery phrase and session tokens confidential. We hold no copy of your recovery phrase and cannot restore access to an account whose phrase has been lost.
All activity that occurs under your account, including activity by devices you have paired and anyone you share your recovery phrase or session tokens with.
Keeping your API keys secret. A key is shown once and we keep only a hash of it. Anyone holding a key can use the API as your account until you revoke it, though no key can create keys, manage sign-ins, close the account or make payments. Do not put a key in code you publish or ship to other people, such as a public repository, a website or an app. If a key is exposed, revoke it in the app.

Tell us promptly at support@mailcycle.email if you believe your account has been compromised.

You must be 18 or over to create an account, and sign-up asks you to confirm it.

4. Devices, AI agents and email addresses

Pairing a device issues it a credential scoped to that device. You are responsible for the devices you pair and for revoking any device you no longer control. Revocation is available to you at any time in the app and takes effect immediately.

An Agent is a paired device for the purposes of these Terms, and you are responsible for it in the same way. In particular:

Mail an Agent sends is sent by you. You are responsible for its content and recipients, and for choosing a send mode that fits what you let the Agent do. Mail an Agent reads may contain instructions written by its sender, and an Agent may act on them.
An Agent passes the mail it reads to an AI model provider of your choosing. That provider acts for you, not for us, is not our subprocessor, and handles that mail under your agreement with it. We are not responsible for what it does with that mail.
The Agent's credential and keys are stored on the machine you run it on. Anyone with access to them can read the Agent's mail and send within its limits until you disable or remove the Agent in the app.

Your plan sets the number of email addresses your account may hold. Every address you create counts toward that limit, whether or not it is assigned to a device, and deleting an address frees its place. We will not create email addresses beyond your plan limit, and we will not silently remove addresses or devices to make a plan change fit. A downgrade to a plan that allows fewer addresses or devices than you hold is refused until you delete enough of them.

Email addresses issued on a Mailcycle domain are licensed to you while your account exists and are not portable. On plans that include custom domains, you can bring a domain you own. If your plan stops including it, the domain keeps receiving mail for 21 days and then refuses mail until your plan includes it again. A missed payment is handled as set out in section 8. A deleted address is retired and is never reissued to anyone.

5. Acceptable use

Your use of the Service must comply with our Acceptable Use Policy and all applicable law. In particular, you must not use Mailcycle to evade another service's terms, to create fraudulent accounts at scale, or to receive mail you are not entitled to receive.

You must not:

Reverse engineer, decompile or attempt to derive the source of the Service, except software we publish under an open-source licence, such as the SDKs, or to the extent that restriction is unenforceable by law.
Resell or provide the Service to third parties as a standalone offering without our written agreement.
Probe, scan or test the security of the Service other than under our disclosure policy.
Interfere with or disproportionately burden the Service, including by circumventing rate limits.

6. Your data

“Customer Data” means the mail received at and sent from your email addresses, with its attachments, and the other content we store for you, such as the names and labels you give addresses and devices. We process it for you, under our Data Processing Agreement where that applies. Customer Data belongs to you. We claim no ownership of it. The data about your account itself, such as its id, plan, payments and usage, is not Customer Data: we are its controller, and our Privacy Policy covers it.

You grant us a limited licence to host, process, transmit and display Customer Data solely to provide and support the Service, to maintain its security and integrity, and as otherwise instructed by you. We do not use Customer Data to train machine learning models, to build advertising profiles, or to sell to anyone.

You are responsible for having the necessary rights and, where required, consents for the personal data processed through your account.

7. Plans, fees and billing

Fees are those shown on our pricing page for your chosen plan when you buy it. A plan bought in the iOS or Android app costs the price the App Store or Google Play shows you at the time. Enterprise plans are priced by arrangement, and their fees are those in the written agreement we sign with the Enterprise customer.
Card payments on the website are sold by Polar as merchant of record, on Polar's terms for the payment itself. Card and in-app subscriptions renew automatically on the provider's monthly billing date until cancelled. A cryptocurrency payment through NOWPayments covers 30 days. On the website, card or cryptocurrency can also pay into your account balance, which renews your plan every 30 days. In these Terms, a “month” of a plan means that paid period.
Payment is due in advance. For a card payment, Polar adds any VAT or sales tax due where you live and shows you the total before you pay. A cryptocurrency price is the total you pay: no tax is added to it.
Account balance. On the website you can pay an amount between $15 and $2,000 into your account balance. Your plan takes its monthly price from the balance every 30 days until the balance no longer covers it, after which the renewal is unpaid and section 8 applies. Where you also pay by card, the balance pays first: a month it covers is not charged to the card, and no month is charged twice. While the App Store or Google Play bills your plan, the balance is left alone. If that subscription ends, the balance pays for the plan again from the date it ended, and a card is only charged again if you start a new card subscription.

The balance can only be spent on Mailcycle plans. It is not a deposit, earns no interest, and cannot be withdrawn as cash, transferred to anyone else or exchanged. It does not expire while your account exists. Outside the cases below, it is not refunded.

We refund the part of your balance that you paid for and have not spent (your “unspent paid balance”), to the payment method you used: (a) if you are a consumer and cancel a top-up within 14 days of paying it, whatever part of that top-up is still unspent, with no deduction; (b) if we end these Terms, close your account, or stop providing the Service or your plan, for any reason other than your breach of these Terms; (c) if you end these Terms under section 2, 7 or 16, or section 5 of our Data Processing Agreement, because of a change we made; (d) if you are a consumer and ask us for it before you delete your account; and (e) wherever else the law requires it, for example as a price reduction if we did not provide the Service with reasonable skill and care.

If we close your account because you broke these Terms, we refund your unspent paid balance less anything you owe us and our reasonable costs caused by the breach, unless we reasonably believe the payment was fraudulent or has been reversed, or the law does not allow us to pay it.

Credit we give you free of charge, such as a goodwill credit, is not paid balance. It is never refunded or paid out, and it ends with your account. Free credit is spent before balance you paid for. When your account is deleted, any balance is deleted with it and cannot be restored or refunded afterwards, so ask before you delete: the delete screen shows you how, and our Refund Policy says the same.
Upgrades take effect once payment is confirmed and start a new paid period. There is no proration.
Paying again for the plan you already hold extends it from its current renewal date.
Moving to the free tier during a month you have paid for stops the renewal and keeps your plan until that month ends, then moves the account to the free tier. Choosing your current plan again before it ends cancels that and starts renewals. Moving between two paid plans is a new month and is paid for like any other purchase. Downgrades are subject to the check in section 4, and the unused part of a period is not refunded. While an in-app subscription is still renewing, a change is refused: cancel it in the App Store or Google Play, and the plan moves to the free tier when the paid period ends.
Cancelling stops future renewals. You can cancel in the app under Plans & Billing → Cancel subscription: the plan stays until the end of the period you paid for, nothing more is charged, and the account then moves to the free tier. A subscription billed by the App Store or Google Play is cancelled in the store, which the app opens for you. If your first plan payment has not been used for anything the plan adds, we refund it in full if you ask within 14 days, as our Refund Policy sets out; a plan paid from the balance is refunded to the balance. Separately, if you are a consumer you have a legal right to cancel each new plan purchase and each top-up within 14 days, from Plans & Billing → Cancel within 14 days, as section 5 of the Refund Policy describes. Other fees already paid are not refunded, except as these Terms say or where the law requires it.
Please ask us before disputing a payment with your bank. Our card provider does not tell us about disputes: a card payment that is reversed reaches us, if at all, as a refund, and is recorded against your account as one. The plan is not taken away automatically: it runs to the end of the period that payment paid for and is not renewed. We may mark the account past due, or suspend it under section 11.
If a renewal fails or is not paid, we notify you where notifications are turned on. If it is still unpaid a day after the renewal date, the account is paused as described in section 8.

We may change our prices. A price increase applies from your first renewal at least 30 days after we announce it as section 17 describes. If you do not accept it, you may cancel before it applies, and if you also end these Terms, section 7 says what we refund.

8. The free tier and beta features

The free tier is provided so you can evaluate the Service, and has no fixed term. It has lower limits than the paid plans, including a limit on paired devices. We may change those limits, or end the free tier, on at least 30 days' notice on our notices page, or at once for an account that breaks these Terms.

If a paid plan is still unpaid a day after its renewal date, the account moves to the free tier and anything beyond the free tier's limits is paused for 21 days. The oldest email addresses and the most recently active devices, up to the free tier's limits, stay active. Addresses on domains you brought are paused as well. Mail sent to a paused address is still accepted, within your plan's monthly allowance, and held without being shown to you; a paused address cannot send, and mail it already had stays readable. Paused devices are disconnected and API keys stop working. Paying for the plan within the 21 days restores it and everything paused, and delivers the held mail. If it is not paid, whatever is still paused is permanently deleted with the mail held for it, deleted addresses are retired, and the account stays on the free tier, which you can upgrade from at any time. Enterprise plans are invoiced by arrangement and are not paused this way.

Features marked beta, preview or experimental are provided as-is, may change or be withdrawn without notice, and are excluded from any service level commitment.

9. Availability and support

We aim to keep the Service available continuously, and we perform maintenance with as little disruption as we can. No plan has an uptime guarantee unless an Enterprise customer's written agreement gives one.

Support is provided by email and from Support in the app. We aim to reply to support requests within one business day and to security reports within two business days; these are targets, not guarantees. Requests are answered in order of the support level on the pricing page: Priority first, then Standard, then Basic. Dedicated support is provided as set out in an Enterprise customer's written agreement.

10. Intellectual property

The Service, including its software, design, documentation and trade marks, is owned by Mailcycle and its licensors. These Terms grant you a limited, non-exclusive, non-transferable right to use the Service while you have an account, and nothing more.

Software we distribute for you to run yourself is licensed under the licence it ships with: the SDKs under the Apache License 2.0, and the mailcycle-mcp package under its own licence. Where that licence grants you more than this section, it applies to that software.

If you give us feedback or suggestions, we may use them without restriction or obligation to you. We will not identify you as the source without your permission.

11. Suspension

We may suspend your account or specific email addresses where:

Use of the account violates the Acceptable Use Policy or applicable law.
The account poses a security risk to the Service or to others.
A payment is reversed or charged back.
We are required to suspend by law or by a competent authority.

We will give notice and an opportunity to fix the problem where it is lawful and safe to do so. Where the risk is immediate, such as active abuse or a threat to the integrity of the Service, we may suspend first and notify promptly afterwards. Our notice says what we restricted, why, and how to ask for a review, unless the law or someone's safety prevents us from saying so.

12. Termination

You may stop paying at any time by cancelling in the app under Plans & Billing → Cancel subscription or in Polar's customer portal, cancelling an in-app subscription in the App Store or Google Play, or not paying again for a 30-day cryptocurrency period. When the paid period ends, the account moves to the free tier under section 8. You may terminate these Terms at any time by deleting your account in the app, as set out on our account deletion page. Deleting the account cancels a card subscription with Polar at the same moment; if that fails, we stop it when its next charge arrives and refund that charge. Deleting the account does not cancel a subscription billed by the App Store or Google Play: cancel it in the store, or the store will keep charging. If your account balance holds money you paid in, the app asks you to confirm that it will be lost, and offers to ask us for it first (section 7). We may terminate for material breach that is not remedied within 14 days of notice under section 17, or immediately where the breach cannot be remedied. We may also end these Terms, or stop providing the Service or a paid plan, on at least 60 days' notice under section 17. If we do, we refund any part of a plan period you have paid for that falls after the end date, and your unspent paid balance (section 7).

On termination:

The account, its email addresses, messages and devices are removed from the live database immediately, and are gone from our database provider's restore history within 30 days. Paired devices return to the pairing screen. Deleted addresses stop receiving mail and are never reissued.
Export anything you need first, in the app under Settings → Export data. What we keep after deletion is set out in our retention schedule.
Any account balance is dealt with as section 7 says: refunded where section 7 requires it, and otherwise deleted with the account.
Fees accrued before termination remain payable.

Sections 6, 10, 13, 14, 15 and 17 survive termination, and so does section 7 for any refund or fee still owed.

13. What we promise

We will provide the Service with reasonable skill and care and as it is described in these Terms and on our website.

If you are a consumer, the law gives you rights if a service is not provided with reasonable skill and care or as described, and nothing in these Terms affects those rights. Citizens Advice, or the consumer advice service where you live, can tell you more.

If you use the Service for a business, we give no promise beyond the first paragraph of this section, and every term that would otherwise be implied by law is excluded to the extent the law allows.

Email is not a guaranteed delivery medium. We do not control the servers that send mail to you, and we do not warrant that every message sent to your email addresses will arrive, arrive intact, or arrive within a particular time. Do not rely on Mailcycle as the sole channel for anything safety-critical.

Mailcycle deletes mail when the retention window you set ends, cannot recover mail once it is deleted or once your recovery phrase is lost, and does not back up message bodies or attachments. Keep your own copy of anything you need to keep: Settings → Export data.

14. Our liability

If you are a consumer. We are responsible for loss or damage you suffer that is a foreseeable result of our breaking these Terms or failing to use reasonable skill and care. Loss is foreseeable if it is obvious that it would happen, or if we both knew it might happen when you accepted these Terms. We are not responsible for loss that is not foreseeable, or for loss you could have avoided by following section 13's advice on keeping your own copy of mail. We supply the Service for private use: if you use it for a trade, business or profession, the next paragraph applies to that use.

If you use the Service for a business. Neither of us is liable to the other for loss of profits, revenue, business, goodwill or anticipated savings, for loss or corruption of data, or for any indirect or consequential loss. Each party's total liability arising out of or in connection with these Terms, in contract, tort (including negligence) or otherwise, is limited to the greater of the fees you paid us in the 12 months before the event giving rise to the claim and US$100.

For everyone. Nothing in these Terms excludes or limits liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, or any other liability that cannot lawfully be excluded or limited, or your obligation to pay fees that are due.

15. Indemnity (business customers only)

If you use the Service for a business, you will indemnify us against claims brought by third parties, and the reasonable losses and costs arising from them, to the extent they result from your use of the Service in breach of these Terms or the Acceptable Use Policy, or from Customer Data infringing a third party's rights. We will tell you promptly of any such claim and let you take part in its defence. This section does not apply to consumers.

16. Changes to these terms

We may change these Terms to reflect changes in the law or in regulators' requirements, changes to the Service, its plans or its payment options, changes in our costs or suppliers, or security needs, or to make them clearer. We will announce a material change as section 17 describes at least 30 days before it takes effect, unless the law or a security need requires it to take effect sooner, in which case we will say why. A change that only helps you can take effect when we announce it.

If you do not accept a change, you may end these Terms before it takes effect by deleting your account, and we will refund any part of a plan period you have paid for that falls after the change takes effect, and your unspent paid balance (section 7). If you keep using the Service after the change takes effect, the new Terms apply to you.

Each change is recorded on our notices page. We keep every version of these Terms and will send you any of them on request; the receipt you can save after a payment names the version that applied to it.

17. General

Governing law and courts. These Terms are governed by the law of England and Wales. If you use the Service for a business, the courts of England and Wales have exclusive jurisdiction. If you are a consumer, you may bring proceedings in the courts of England and Wales, or, if you live in Scotland or Northern Ireland, in the courts there. If you live outside the United Kingdom, you also keep the protection of the mandatory consumer laws of the country where you live, and you may bring proceedings in its courts.
Assignment. You may not assign these Terms without our consent. We may transfer them to an affiliate, or to a buyer of our business, provided that doing so does not reduce your rights under them.
Entire agreement. These Terms, together with the policies they incorporate, the Data Processing Agreement where it applies and, for an Enterprise customer, the written agreement signed with us, are the entire agreement between us on this subject.
Severability. If a provision is unenforceable, the rest remains in force.
No waiver. Not enforcing a right is not a waiver of it.
Force majeure. Neither party is liable for failure to perform caused by events outside its reasonable control.
Notices. We give general notices, such as changes to these Terms, our prices or our policies, subprocessor changes and service notices, on our notices page at mailcycle.email/notices and in its feed, and we also send them to each account in the app, to its support inbox. An account whose app has not signed in since 25 September 2026 cannot receive notices in the app, and is notified by the notices page alone. A notice for your account alone is sent in the app in the same way, with a push notification on devices where notifications are on. We hold no email address for you, so we do not notify you by email. You notify us at hello@mailcycle.email.
Third parties. No one other than you and us may enforce these Terms, except that data subjects have the rights the Standard Contractual Clauses in our Data Processing Agreement give them.
Complaints. If you have a complaint, write to support@mailcycle.email or use Support in the app. If we cannot resolve it, we will tell you in writing which alternative dispute resolution body could consider it and whether we agree to use it.

18. Contact

Northlab Studios Ltd, 167-169 Great Portland Street, London W1W 5PF, United Kingdom
hello@mailcycle.email