Unable to send emails

[StevenRamshaw]

When sending emails I get a message saying unable to reconise server. 

[Mark39]

@StevenRamshaw are ypu using an email app? Are,you able to send successfully if you log into your email account here: www.sky.com/signin/email

[Brian+Penfold]

I cant either!  Trying to send from my sky account to my outlook account on outlook/365 and getting system administrator: undeliverable.

Your message did not reach some or all of the intended recipients.

I've not made any changes and have been sending this way for years. Only my personal sky mail account affected, and the webapp is fine

[Mark39]

@Brian+Penfold for clarity, are you getting the 'undeliverable' message when sending via an app? Do they send ok when you're using webmail via sky.com?

[twilight+princess]

Are you sending the email to multiple receipients? If yes then some of the recipient's accounts are blocking the email thinking it is spam, try sending to a smaller number of recipients or even sending individual emails to those which return the undeliverable message.