unable to send emails from lineone email account on iphone 6s

Many thanks for your help Chris, the apple guru's are at a loss also - I have a call into the email provider and awaiting a call back they insist the settings are correct but I think Apple think its after the latest IOS update something is preventing the sending of the emails on a security issue which we cant override as the SMTP setting are rejecting on 'incorrect username password' but both are definitely correct. Hopefully we can get it sorted but thanks for the help. If anyone out there has had the same problems please do get in touch thanks.

Hi

Very strangely after an exhaustive search of solutions emails suddenly started sending again! The engineers at Apple did become involved but not sure if they have done something or Talk Talk the lineone account provider -but many thanks at least at present I can send emails again. Hopefully the next IOS update will not cause so many problems!!