Reporting spam from a Fastmail user

If you received an email you think was spam, forward the entire email (with complete headers) to We’ll analyse it to see if the relevant Fastmail addresses exist and/or have been locked and send a report back to you.

Email blocking

We have a strict zero-tolerence policy for spam being sent from our service, and we’re more than happy to work with other sites that believe they are receiving spam from us to ensure the accounts are blocked and legitimate mail is accepted. The vast majority of the time, the spam turns out to be from somewhere else entirely, just with forged headers to make it appear like it comes from Fastmail.

If a site is blocking email from Fastmail, please send a link to this help entry to postmaster@<>, webmaster@<>, abuse@<> and support@<>. You’ll have to do it from a non-Fastmail account obviously…

Opt-in mailing

Our terms of service specifically prohibit “unsolicited commercial email”. Remember that even one complaint of an unsolicited email where the email clearly shows that it’s commercial is enough to break the terms of service, so please be careful.

An important first point: it’s impossible to purchase a list and meet these terms. A user may have solicited communication from some company, but they didn’t solicit it from you, they solicited it from the company you are purchasing the list from. Any time you purchase a list and email the addresses on it, you will always get complaints of unsolicited commercial email, and will be even liable to legal action in some jurisdictions.

If you wish to use your Fastmail account for drumming up business, you may do so as long as it is to people who have solicited the communication with from your company, and you have evidence to prove this. To ensure you have the necessary evidence, you will need to request a confirmation email from the person signing up. Your opt-in confirmation should be short and simple and contain some key information to confirm the source of the opt-in. The subject should be something like:

Confirmation of subscription to <list name> for <email address>

The text should be something like:

We have received a request to subscribe your email address,
<email address>, to the <list name> mailing list. To confirm
that your email address should be added to this list, click 'reply' and
then click 'send', leaving the subject and message unchanged. If you do
not want to sign up for this list, simply delete this message.

The request details are as follows:

Date: <date and time>

Email Address: <email address>

Request source: <url>

From IP: <source ip>

The all-important details section shows the date and time that the opt-in request was made, the address that is being signed up, the URL that the request was made from, and the IP address of the person that clicked that URL.

If you use this confirmed opt-in strategy, including providing the details of the source of the opt-in, and avoiding any advertising or promotion in the message itself, we would be happy for you to use your Fastmail address in future messages to that user. So that we can confirm this in the case that one of your recipients claims that they did not opt-in, you should ensure that you do the following:

The sender’s IP

If you send an email via the Fastmail web-interface, an extra email header is added: X-ME-Sender, which includes a cryptographically secure encrypted version of your username and IP address. This allows us to determine the account an email was sent from if it is reported to us as spam. The information cannot be decoded by anyone but us. We can still track abusers, but don’t give out the IP address of our customers.

Note that if you send via the SMTP server, then a standard Received: header is added, which will contain your IP address.