Recently, Gmail has been rejecting my email from any of my own hosted domains when sending the emails through the BT smtp server (which I've been doing for years....
Gmail helpfully says I need to add SPF, DKIM or DMARC records......
I use Freeola as my host..
Has anyone else had issues? the old BT mail clients you could define alternate senders.
There have been a couple of posts like this. It would appear Gmail are tightening up. Can't help with DKIM or DMARC records to add but you can add v=spf1 mx a ip4:213.120.69.0/24 a:btinternet.com ~all to your SPF record along with your domain host's details