----- The following addresses had fatal errors -----   

   [Status: Error, Address: <friend@btopenworld.com>, ResponseCode 421, Too many messages (1.5.7.1) on 2017/09/08 13:10:33 BST from un-validated IP address: 135.84.80.216. Please add a SPF record for the domain exxxxs.org.uk to your DNS or ask your Broadband Provider / Domain Registrar to do this, we will be unable to deliver email until this is done due to the volume of email being sent from this IP address. Guide for bulk senders www.bt.com/bulksender]

I have set up SPF record for my domain (some years ago) so what is happening?

Robert