I have found the solution for using one Yahoo! Mail account with multiple external e-mail addresses. You do need the paid Yahoo Mail! service to be able to process mail both on the BB and in the web mail interface.
I have two email addresses forwarded to my Yahoo Mail! account:
. My Yahoo Mail! address is
In Yahoo! mail you will have to set up two accounts (skipping the mail server settings), one with
as reply address and one with
as reply address. Now you can create and reply to mail with the correct from address set.
Then you need to use the option to add a separate e-mail address to your Yahoo! Mail account. Let's set this additional e-mail address to "firstname.lastname@example.org".
In BIS 2.0 you set up two accounts: One for
and a second for
. Set reply to address for these accounts to
for the first one, and
for the second one.
You have to create two filters for each of the BIS accounts: For the
account the filters are set not to push mail To or Cc'ed to
. For the
account the filters are set to not push mail To or Cc'ed to
. Now you will have mail sorted to the correct BB inboxes and get the correct from address set when replying, and all your outgoing mail will be stored in the Yahoo! Mail outbox.
Limitations: You can only have one signature in Yahoo! Mail, so mail from both accounts will have to have the same signature when sent from Yahoo! Mail (this is not the case for mail on the BB where the signatures are set in BIS). Also, if someone sends mail to both your addresses it won't be pushed to your BB at all (I will try to find a way to get around that when time permits).
This works for me now. However, I have not been using it for long, so please do not hang me if there are issues with this setup I haven't thought of