There was a problem with sending email from an Iphone 4S. Email could be received, but not replied to. It was set up as a POP account. I messed around a couple of days before hitting on this facility and then red the trouble shooting instructions which probably helped. In the POP account there appeared to be a setting for sending email that said you would use this POP account to send for any sends, essentially. so I tried setting up an exchange account while this one was still active, and found out that I still could not send.
So yes, looked at the password strength and yes it was lousy. did not pass muster at all. Was just a persons name. So spiced it up as per instructions but still no send. So finally decided to delete both shaw mail accounts, the POP account and the Exchange account and start all over. finally it worked and the mail started to send immediately.
So was it the password, was it the dual accounts, was it the pop account box that said to use the pop account to send email and then complained about the password etc. don't know, but hope this helps some one.
I happened to be in the southern USA while having this problem. but can now send and receive email ok. problem solved.