How does a Mail Client identify Marketing Mails as Marketing Mails?

[DerFabian]

Hello Community,

my question is out of curiosity more than a real issue:

If I sent a marketing email from HubSpot some mail clients identify it correctly as marketing medium and flag it as such.

I wonder what are the technical parameters that allow mail clients like Outlook to do so:

Does HubSpot deliver this information with the email (like in the email header) or is it based on the obligatory unsubscribe link at the bottom or something entirely different?

Thank you very much!

[karstenkoehler · Accepted solution]

Hi @DerFabian,

Receiving email service providers can tell by the email authentication whether an email is marketing or sales 🙂 https://knowledge.hubspot.com/marketing-email/manage-email-authentication-in-hubspot

This type of authentication only applies to bulk emails, not to one-to-one emails.

Best regards!