I'm trying to find my old vodafone inbox in order to transfer emails to my new outbox address, but can't find them (?)
If you have the account details etc, you can simply import them into Gmail/Outlook/software of your choice.
But I can't find or open my old Vodafone email account. Therefore I can't transfer the old emails over to my new Outlook account. Meanwhile all new emails are going to my Outlook account via Vodafone.