Why do you have a mailbox with a UK street address? Perhaps you use expost because you don't want anyone to know where you live or work, or that you have relocated abroad. So, do you really want to reply to letters, or return that official form, with a foreign stamp on the envelope. . . or an incorrect postmark?
Outpost is a unique service that is available to both Private and Business mailbox customers. Use outpost and your letters or parcels will be delivered, by the Royal Mail, with UK postage stamps and a postmark that matches your mailbox address!