What is the issue?
Some customers add include:spf.titan.email to their SPF records, which is not the TitanHQ SPF include: statement. include:spf.titan.email belongs to a different company, called Titan.
What is the solution?
If you are using https://cloud-out-c.spamtitan.com for outbound mail, the TitanHQ include: statement is:
include:_spf_cd.spamtitan.com
If you are using SpamTitan Private Cloud, outbound and inbound mail go through the same server(s), so you can add mx to your SPF record.