I have the following SPF record:
v=spf1 include:servers.mcsv.net include:u3556354.wl.sendgrid.net ?all
I then sent an email to http://dkimvalidator.com but they gave me the error:
Result: permerror (Included domain 'u3556354.wl.sendgrid.net' has no applicable sender policy)
Full message is here:
Looking up TXT SPF record for thedealerapp.co.uk
Found the following namesevers for thedealerapp.co.uk: ns2.wixdns.net ns3.wixdns.net
Retrieved this SPF Record: zone updated 20170509 (TTL = 69760)
using authoritative server (ns2.wixdns.net) directly for SPF Check
Result: permerror (Included domain 'u3556354.wl.sendgrid.net' has no applicable sender policy)
How do I fix this?
Like it says: the hostname at u3556354.wl.sendgrid.net does not publish an SPF record. Sendgrid's documentation (which should have been the first place you looked) says you should use just plain sendgrid.net.
Having ?all as your default action means that your SPF record is almost completely ineffective and will not do anything to prevent forgeries; you should use ~all instead.
So your SPF record should be:
v=spf1 include:servers.mcsv.net include:sendgrid.net ~all