Struggling with Mail Programs

I just have to sit here and vent my total frustration with e-mail programs today. I have am trying to get a mail program to work on my system here and it is the most agravating thing to do since it is supposed to be so easy to just connect it to any remote mail server and download your mail. the documentation says it is easy but that is just a real lie cause every time I try to get this program to connect to the remote server I get another strange kind of error. I have tried alot of different mail programs but this Thunderbird Mail is supposed to be the easiest to use and I do like it but try to get it to work with any other account besides Gmail and it does not work.. Yahoo and the rest of the mail accounts I have and don't seem to work with it but yet it does support multi account and multi identities all in the same program.. I got another error when trying to connect it to Yahoo early this morning which says unable to send user login information and pop user is not allowed access. Hmmmm.. I got to say in 30 years of computer usage I thought I pretty much encountered most every error that computers and the internet could throw at me but this one has me stumped. I am trying to use thunderbird mail program and would like help if someone online has any ideas or suggestions just leave it in the comment section or e-mail me if you know the solution to this problem. Oh.. yes and one other thing it is doing is to ask for the password to my yahoo account then I type the correct password and then it gives me a wierd error response message telling me pop user not allowed. I have have played around with the server settings but that does not seem to fix the problem which usually is the right solution and fixes the server assignment issue. I look down at the left side bar at the bottom of the screen and it says I am connected to yahoo mail host but fails in sending login information which totally puzzles me as to why it is doing this.. If any one can help me it sure would be appreciated and maybe you can tell me why all mail programs are really hard to get Yahoo and Hotmail to work wiith... Oh by the way Gmail works just fine!! Why does Yahoo allways be a pain in the neck just like Hotmail does the same thing to setup and use with remote mail programs like Thunderbird and Windows Mail and other programs like it?? I think they do it so only advanced computer users can figure out how to use it and get the benefits out of the program..

Thanks===>> Rick N.