Gmail emails scheduled using Hubspot Chrome Extension get bounced
Scheduled emails have this additional message header:
The bounce I get every time is:
Message rejected. See https://support.google.com/mail/answer/69585 for more information.
Google support specialist advised to add Hubspot to my SPF records.
In case of Google the line to copy to SPF is: "include:_spf.google.com"
What should I paste for Hubspot?