We have recently seen where some of our customers are adding the following to their SPF records: include:spf.titan.email


That is not our SPF include: statement.


That is a different "Titan":

TITAN | Help Center


If you are using https://cloud-out-c.spamtitan.com for outbound mail, our include: is this:
include:_spf_cd.spamtitan.com


If you are using SpamTitan Private Cloud, since outbound and inbound mail go through the same server(s), you can add "mx" to your SPF record.


If you have any questions, create a support ticket at:  https://helpdesk.spamtitan.com/