Sorry to take so long to thank you for your help. I had a go at the computer today, worked through everything. As far as I could see everything, firewall settings etc are ok. They use the windows firewall. Avast will allow emails in but will not send. After some hours of pulling my hair out I lost my temper and just unchecked the box to scan outgoing mail. At least now they can receive as well as send emails! Thanks fo your help.