Apple Mail SMTP is offline

[Adfloor80]

I can send loads of emails, receive loads of emails etc all no issues

yet when I try and send an email to one particular email address, which is the correct email address I keep getting the above message and email just sits in my outbox 

they have added my email address to their safe list etc and still it's no going through 

I don't get it, can anyone shed some light please 

[Mark39]

Are you sending via the Apple Mail app? Can you send to this contact if,you access Sky Yahoo Mail via sky.com using your browser?

[Adfloor80]

I've tried via both apps on my lpad and iPhone 

works for any other email address but not this one I'm trying to send too

[Mark39]

I was suggesting trying here, not via any app: https://www.sky.com/signin/email