Wrong Username/password Message

[#1]

The last three afternoons, when trying to check email on my iphone, I get the message that my Verizon server is not accepting my username or password. I have no problems with mail in the morning.  When I get home I check my email on my Mac desktop computer and when the mail arrives on the computer, it also then appears on my iphone.  However, I also occasionally have trouble receiving and sending email from my home computer, either the mail does not arrive or I am asked for my Verizon email password to send a message.  I have not seen these problems before this week.  Anyone have an idea what might be going on?  Thanks.

[#2]

Verizon email is not very good, and has issues like that, quite a bit....

youd be happier with a gmail or hotmail account, I bet....

[#3]

Had some time to check out this issue today. It appears to not be entirely a Verizon issue.  I can access my email on my iphone while using a wifi connection but when on the at&t cell service, I get the username/password rejection message.