I have a PO BoxÂ®. You can redirect mail from a PO BoxÂ® for a maximum of six months and the PO BoxÂ® must remain open during the period of the Redirection. You can redirect mail to a PO BoxÂ® for a maximum of two years.e aware of timings. When your mail is redirected, it will be sent to the delivery office that serves your old address first. From there, it will be forwarded using our 1st Class Mail service to your new address or, using International Standard if you are moving to an address outside the UK.