There was an issue sending your email. This email wasn’t sent.

I started sending 1 to 1 emails today, and the first few sent just fine, then I started getting:

“There was an issue sending your email.
This email wasn’t sent.”

Is there a reason for this?

I have a test contact I sent an email to verify as I know that contact is correct (it’s my email adress, and I have already sent and recieved email) but even that produced the same error message.

Hey there,
It can be one of the reasons written here: Email error: 'There was an issue sending an email to this contact' If not we can look at it again
Cheers

This email wasn’t sent: this message appears when the contact cannot be sent an email and HubSpot was unable to determine a specific reason for the failure.

- This is what that page says applies to me, as far as I can tell.