Sendgrid is driving me up the wall!

[omarfilip]

There are two different domains there:

terrain.io appears to have a Mailgun spf verification:

https://centralops.net/co/DomainDossier.aspx?addr=terrain.io&dom_dns=true&dom_whois=true&net_whois=true

Perhaps a mixup of the two somewhere in your settings?