Incoming email on Runbox alias

Hi - I am a new user of Runbox and have set up a run box alias using “@rbx.email”.
I have had a few responses on this alias but one fairly close friend has had his email to me, returned to him with an “unable to be delivered” message. His ISP is “@sky.com”.
I am not very techy, but does anyone have any suggestions how I or my friend can get round this?
Thanks

Hi @TheNonno and welcome to the community – and apologies for the late reply.

What you describe sounds like a temporary error or possibly related to the network or sending service.

If the problem continues please contact us via https://support.runbox.com with more details about the returned message. Our technicians will then be able to help you track down what may have happened to the email.

Thank you!

– Geir

Thank you Geir - the problem may have been at the other end of the email, as my friend has now sent other emails which have arrived in the normal way.

So thank you for your response, and everything is running smoothly now.

Regards

Tim Johnson