Email Connection/Send/Receive Issues
One of the reported issues stemming from the 8.0.1 Update includes stored passwords becoming unusable; you will probably need to (and should, for security reasons) re-enter your passwords, and if possible, not keep them stored on your phone/device.
You will also need to recheck/re-enter all of the relevant settings in your mail program: IMAP server, username and password, SMTP server, username and password, and the port numbers used. You can find the appropriate setup information on our help pages.
Another avenue to investigate is if you’ve installed a virus/malware scanner on your computer; such scanning programs can interfere with the outgoing and incoming settings on email clients.
iOS Update Issues Remedies
One of the recommended procedures for multiple issues on your iOS device (running 8.0.1 or 8.0.2) is to reset all settings; this will help provide a clean slate in your settings and allow you to make sure no settings have been modified by the update.
A number of users have reported connectivity issues with their device, following the 8.0.1 upgrade (and in a limited fashion 8.0.2). These issues affect wi-fi and wireless connection methods, and can usually be resolved by resetting the network settings. If you are having trouble receiving or sending email, make sure that it isn’t a matter of the device not connecting before you get deeper into diagnosis.