To configure IMAP access for your BlackBerry, just follow these steps:
From your BlackBerry home screen, select the BlackBerry Set-up icon, then choose Personal Email Set-up. (On older devices, just look for the Personal Email Set-up icon.)
Select Personal Email Set-up.
Accept Terms and Conditions.
On the 'Email Account Set-up' page, enter email@example.com (any of your Pobox addresses) but leave the 'Password:' field blank. Select Next.
You'll see a screen that says 'We were unable to configure youraddress @pobox.com.' Select "I will provide the settings to add this email account", then Next.
Select Internet Service Provider Email (POP/IMAP), then Next.
Select I will provide the settings to add this email account, then Next.
You'll see 'The BlackBerry Internet Service could not configure firstname.lastname@example.org email account.' Select "Provide The Settings" to continue.
In the 'User name:' field, enter email@example.com (any of your Pobox addresses). Then enter your password in the 'Password:' field.
In the 'Email server:' field, enter 'mail.pobox.com,' then select Next.
If IMAP access was successfully configured, select OK.
Below your newly added Pobox address, select Edit.
Select Advanced Settings at the bottom.
Make sure the port is set to '465' and 'Use SSL' is set to 'Yes.'
There should now be a new mailbox icon on your BlackBerry home screen labeled with your Pobox address. Once you see this icon, follow these steps to ensure proper configuration:
Open the mailbox icon.
Open the menu by pressing the jog wheel or BlackBerry menu button, then select Options.
Select Email Reconciliation.
Confirm the following settings: Delete On: Mailbox & Handheld, Wireless Reconcile: On, On Conflicts: Mailbox Wins.