Cannot send emails from S7 using Outlook and BTYahoo

[Android Central Question]

Why aren't emails sending from my S7 (this is new issue following resetting password. I have a BTinternet email address. I can receive and send emails from Outlook on my desktop. Ditto email to and from ipad and BT webmail. However I can only receive and not send emails from S7. I have checked all the email settings for the email address and BT server, both incoming and outgoing using SMTP both with and without authentication for sending emails. Nothing has worked. Is there a setting somewhere else I need to change. I've spent hours trying to fix this but nothing suggested so far seems to work. Can someone please help me?