Email not updating on HTC One

[#1]

Issue just happened recently. Webmail shows I am receiving emails but when I update on my phone the last email showing is 28th September. No settings have been changed in my phone and the account was working fine for months. Have tried deleting and reinstating the account, but no joy!
Any ideas?
Thanks,
Ross

[#2]

Hi Ross,
How are you accessing the mailbox on your phone? Using IMAP or POP3?
If you're using IMAP and Webmail works, then so should your phone (Webmail access is over IMAP). You are using the same username for both aren't you?
If you're using IMAP and you don't mind reconfiguring stuff, then it might be an idea to try clearing the app data on Android.