As the issue is impacting a number of people there's a team working on the problem. Which email domain are you using (e.g. tiscali / lineone / another) and is it just webmail not email sent from a client like Outlook or Thunderbird or a gMail app, for example?
Service status is reporting a fault and there will be updates:
"We're aware of some customers having issues when they try sending, replying or forwarding emails. Our engineers are looking into this as a priority, and looking into fixing as soon as possible. We apologise for any inconvenience caused."
Hi kbutler1960, the email team have advised that they've fixed this problem now. Are your emails sending normally now?