How email works with Impact Stack

For your email to target actions to be successful, the emails need to land in the inbox of the target.

To ensure this, we use all technical means to stay off any spam blacklists and we also get our server whitelisted for big mail companies. We have the best rating, which means you won't find Impact Stack emails in your junk or spam inbox.

In general, more onion adopts a very strict policy around email standards to ensure that deliverability is as good as it can be.

When we set up your Impact Stack installation, we'll have set up a subdomain such as for your Impact Stack, with specific DNS settings which you get from us

Our email server is then the official email server for this specific subdomain - (but not for Your Impact Stack thank you emails, notifications and confirmation emails are very likely to be successfully delivered because the Impact Stack server is authorised to send emails using your subdomain.

Why do the supporter email addresses look strange in target's inbox?

To ensure that your supporters' emails have the best chance of reaching the target's inbox, we generate a new email address for every supporter using your Impact Stack subdomain, and use this as the sender address. If the target writes an answer to this generated email address, our server receives it, looks up the real supporter address, forwards it to the real address and your supporter will receive it. Other service providers in this sector use a similar approach.

If Impact Stack sent emails which pretended to be coming from the supporter's own email address, there's a strong chance the target would never see them, but neither you, nor the supporter would know. The receiving email server would detect it as spam and if working correctly, wouldn't place the email in the inbox.

Depending on the email client that the target is using, they will normally see the supporter's name in their inbox, and will only see the hashed address once they've opened the email, by which time they're hopefully more interested in reading it!



Here's an example

Your supporter Susan Mayer takes an email to target action using her personal email address

If our mail server were to send an email to the protest target with "" written in the "From:" field, the target mail server would receive the mail and reads the "From:" field. If the field indicates that the mail should be coming from a Google Mail server but is actually sent from the mail server of  it would be discarded as junk, because this is not allowed.

Instead, we generate a new FROM address like and send the email with this address in the 'From:' field. Now the target mail server sees a match between the sending mail server and the FROM address and accepts the mail.

What happens when a target wants to reply to the protester?

The target can simply answer to this generated email address. Impact Stack records the real supporter address ( that relates to the generated one ( When the target answers to the generated email address, our mail server forwards the email to the supporter.

My site sends mails from (or something similar) in the 'From:' field, but I want the! What can I do?

We can't send emails from a real supporter email address. For the same reason, we also cannot send emails to a supporter using the domain of your organisation (e.g.

Our mail server can only send emails for but not for

Again, the domain of the email address in the 'From:' field has to match the domain of our mail server.

So, all the thank you emails or confirmation emails to supporters will have to use an email address using the subdomain you provided us.

However, you can set a REPLY TO email address to whatever you like!

What is the difference between a REPLY TO and a FROM email address?

Your choice of 'From:' email address is limited, but you can set a different 'REPLY TO' address. This can be set to any email address, but a working email address you maintain and have access to is advisable.

What does 'REPLY TO' do? Even if the 'From:' email address is a different one, if you hit reply in your webmail or mail client you will reply to the email address specified in the REPLY TO field.

This sound great! Where can I set this REPLY TO address?

Go to the emails settings of your action. (The URL will follow this format:

There, enable for example the Thank you email as in the picture below.


Have a look at the 'E-mail from address' settings. You first see the default email address, which we configured at your Impact Stack onboarding and which is set in this example to This is the default email address that will be used by default for sending all emails to supporters.

Just below, you see the 'custom e-mail from address', which is set to for this action. As an address is entered here, this address will be used as the REPLY TO address for your supporters to answer you directly, instead of

What else can I customise?

For more details on the general setup of emails, you can have a look at our emails setup userguide.

My site sends mails from and I would like to use for an action

Then, you can add this e-mail address in the Custom 'E-mail from address' field, and as the subdomain matches our mail server, this address will be used to send the emails too, for this action.

In general, if in the custom e-mail 'from' address field you enter an address like, then this address will be used as the FROM email address (not just the REPLY TO).

Additionally, you might want the responses from this address to be redirected to an email box of your choice. By default, no reply-to address will be set for this custom email address. If you want the answers to this email address to reach you, you will need to contact our support team for us to set-up the reply-to address for you.


DMARC: the technical standard underlying all of this

DMARC is an email standard that's been adopted by some of the biggest players and it is a measure to make it more difficult for anyone on the internet to send an email "pretending" to be someone they are not. As far as email servers are concerned, that's exactly what an email to target action does. Our solution is to send all emails to target from authenticated custom domains, matched back onto the supporter's email address.

DMARC means "Domain-based Message Authentication, Reporting and Conformance" and is a validation system that aims to detect email spoofing (emails with a forged sender address) and to give spam a hard time. It provides a mechanism to allow receiving mail exchangers to check if the domain of the mailserver that sends out the emails matches the domain specified in the email address of the 'From:' field and that neither email nor attachments have been modified on the way.


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