Keap
What Keap's own documentation says about Microsoft 365, that its Outlook email sync brings email into Keap and is not described as sending through your mailbox, and how mail written in Outlook is signed.
The Keap page that could be read describes syncing your Outlook email into Keap, not Keap sending mail through your Microsoft 365 mailbox. Choose how your CRM or app sends its mail explains the two ways to send and why.
At a glance
- Can be signed: email you write in Outlook, as any Outlook mail, which Keap's sync can then bring in.
- Cannot be signed: email Keap sends. Keap's page says: "If your business uses Outlook in Office 365, Keap now syncs with your email just like it does for Gmail." and that "Any emails sent by Keap clients to your Outlook email address are automatically added to Keap". It does not say that email sent from Keap goes through your mailbox.
- Status: from Keap's product update of 29 March 2019, as read on 23 October 2026, not tested by Footer365. Nothing newer was read, so Keap may now do more.
What you can do
- Write email that must carry a signature in Outlook. Footer365 signs it like any other Outlook mail, with mail flow set up or the Outlook add-in deployed. Which messages get a signature
- Make sure each person has a Footer365 signature rule.
- Check one message, as described in Mail from your CRM and other apps.
What is not signed
Email Keap sends, because nothing read says it passes through Microsoft 365. Footer365 never sees mail sent from Keap's own servers. A connector into Exchange Online is not an option: Microsoft says SMTP relay cannot be used for a service hosted by someone else. Last resort: a connector to Exchange Online
If it does not work
- A message written in Outlook is unsigned. The signature was not added
- A message from Keap has no
X-Footer365-Relay-Id. It did not pass through Microsoft 365 with Footer365. Mail from our CRM is not signed
Sources
Read on 23 October 2026:
- Keap: Keap email sync, 29 March 2019.
Still stuck?
Tell us what you were trying to do and what you saw. Include the sender, a recipient and roughly when a message was sent, and we can trace it.