Acceptable use policy
Last updated: 1 November 2026
mailchecker checks whether an email address is real and can receive mail. It exists to keep the contact data of businesses accurate and to stop fake or mistyped addresses entering their systems. It is not a tool for unsolicited marketing, and we do not allow it to be used as one. This policy forms part of our terms, and mailchecker ("we") may act on it as described below.
What mailchecker is for
- Checking addresses that customers, subscribers, members or users gave you, so typos and dead mailboxes do not sit in your records.
- Stopping fake, disposable and mistyped addresses on your own signup, checkout and contact forms.
- Keeping transactional email (receipts, password resets, account notices) reaching the people who asked for it.
- Cleaning a list of people who agreed to hear from you, before you write to them.
What you must not do
- Unsolicited marketing. Do not use the service to prepare, clean, build or improve lists for cold email, spam, bulk unsolicited messages or any email sent without the recipient's permission or another lawful basis.
- Addresses you have no right to use. Do not submit addresses that were scraped, harvested, guessed, generated, rented or bought from a list broker, or collected without a lawful basis.
- Finding addresses. Do not use the service to discover whether a person or an address exists at a domain you have no relationship with, to guess addresses, or to build a directory of people.
- Abusing the service. Do not probe, overload or scan it, get around rate limits, credit checks or security, resell it without our written agreement, or use it to harm the reputation of the mail servers we contact.
- Breaking the law. Do not use the service in a way that breaches data protection, privacy or anti-spam law (such as the GDPR, PECR, the CAN-SPAM Act or CASL), or for fraud, phishing or any unlawful activity.
What we do and do not do
- We never send email to the addresses you submit. We only ask the receiving mail server whether the mailbox exists.
- mailchecker is not an email-sending service. It has no features for sending campaigns, sequences or bulk messages.
- We do not sell, share or reuse the addresses you submit, and we do not build lists from them.
Your confirmation when you upload
Before a file is verified, we ask you to confirm that the addresses in it were collected with permission or on another lawful basis, and that you will not use mailchecker for unsolicited marketing. You are responsible for that confirmation being true.
Enforcement
If we believe this policy has been broken, we may ask you for information, limit or suspend your account, remove data, or end the service and refuse a refund for what has been used. We may report unlawful activity to the authorities and to our payment and hosting providers. Signs we look for include very large volumes of newly acquired lists, many addresses at the same domains, and complaints from mail providers.
Report misuse
If you think someone is misusing mailchecker, or an address of yours was checked without your consent, write to [email protected]. We will look into it and answer within one working week.