Impact Stack email deliverability or how we comply to DMARC standard

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 and comply with DMARC. This 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.

What is DMARC anyway?

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.

Essentially, 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.

How do Impact Stack emails comply with DMARC?

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 the official email server for this specific subdomain - (but not for Your thank you emails, notifications and confirmation emails will be DMARC compliant because the server is authorised to send emails from this domain.

Why do the supporter email addresses look strange?

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 and forwards it to the real address and your supporter will receive it.

This has the added advantage of reducing the chance that supporter email addresses could be added to mailing lists by the target. (This is clearly not compliant with GDPR but we know that some targets have done this!)

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 discarted as junk, because this is not allowed according to the DMARC standard.

Instead, we generate a new FROM address like and send the protest mail 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, because Impact Stack saves a mapping between the real supporter address ( and the generated one ( When the target answers to the generated email address, our mail server receives the answer, looks up the real supporter address and forwards the email to the supporter.

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

To comply with the DMARC standard, we not only can't send emails from a real supporter email address, but we also cannot send emails to a supporter using the domain of your NGO (e.g. It's the same reason as described before when sending protest mails from a supporter to a target. Our mail server can only send emails for but not for for the emails to be DMARC compliant. Again, the domain of the email address in the 'From:' field has to match the domain of our mail server. Thus, 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?

With DMARC, 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 DMARC compliant 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

But just for this one 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 a DMARC compliant 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. Per 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.

For all my actions

Then, contact our support team and ask them to change your Impact Stack mail settings :)



Have more questions? Submit a request