I have added an additional email address to an account but it does not show
up as a mailbox in inbox along with 2 other addresses. Also, mail comes in
to general inbox but I cannot send any email...
POP accounts do not have their own inboxes by default, since all the mail
comes into 'my computer', so it ends up in the inbox under 'folders on my
computer'.
However, you can easily set up separate inboxes, and filter the mail into
them with simple rules:
Set up new folders under 'Folders On My Computer', called 'Account A',
'Account B', etc...
Set up a mail rule ( under the POP Mail tab) with:
'If' criteria: Account is '(name of account A')
Action: Move message to folder 'Account A'
Set up a second rule:
'If' criteria: Account is '(name of account B')
Action: Move message to folder 'Account B'
Now, all mail should be filtered into the appropriate folders.