Emails being rejected as Sender prohibited by SPF

[felly55]

When I send emails I get the following message:

" host smtp.mailchannels.net [54.203.146.40]
   SMTP error from remote mail server after end of data:
   550 5.7.1 [BFD] Sender prohibited by SPF
Reporting-MTA: dns; grh47.myukcloud.com

Action: failed
Final-Recipient: rfc822;xxxxxxxxxxxxx [recipient address removed for privacy]
Status: 5.0.0
Remote-MTA: dns; smtp.mailchannels.net
Diagnostic-Code: smtp; 550 5.7.1 [BFD] Sender prohibited by SPF"

I don't know what the myukcloud reference is and I haven't changed any settings. 

Can anyone help me to sort this please--no emails getting through on my Apple Mail platform, which is my main mailing medium.

Thanks in advance

[licquorice]

This has absolutely nothing to do with BT, the problem is with your mail host.

[felly55]

Thank you that’s helpful