I am a student and installed odoo for assignment purpose. I have installed a few apps and loaded the demo data. When I make a quote and send it by email. It says "an error occurred when sending an email".

When I launched it for the very first time then there 2 email errors and 2 message error that " "an error occurred when sending an email. and fir the message  "an error occurred when sending a message"

I have tried custom email servers but they are not working as it says username and possoword are not correct while the same user and password I use to login in to odoo.

I tried uninstalling the latest and trying the older version but problem remains the same. Dont know what to do. 
Any help will be apricated.