E-Mail Won’t Send on iPhone on Wi-Fi

Some Wi-Fi networks may have security measures which don’t permit e-mail
out to the designated mail server. You will get a message that reports
that the mail server that you are attempting to connect was not
available.

To remedy this, turn off the Wi-Fi and go back to the the e-mail, which
will be waiting in the outbox. If EDGE is available, the e-mail will be
sent via EDGE and the designated mail server.

— mb