To verify your email server settings are correct on your iPhone or iPad follow the steps below, this is handy to know if your provider contacts you saying that the settings are changing or that they have maybe detected you are still using old settings:
1)Open Settings
2)Select Mail
3)Select Accounts
4)Select your email address
5)Select Account again
6)To verify your Outgoing Mail Server settings Select SMTP and then Select Primary server, compare settings against those provided to you by your ISP
7)Then select Account
8)To verify your Incoming Mail Server settings, Select Advanced, compare settings against those provided to you by your ISP
9)Once completed select Account
10)Select Done, this will verify your settings, if correct you will see blue ticks alongside your new settings