Is the person who owed you in England/Wales?
You could try sending in your claim form with an application form (N244) and £45 fee (on top of the court fee for issuing the claim - unless you qualify for a fee remission) and ask in the application if the court will give permission for the claim to be served also by email, giving all the reasons you have for this. You can download it from the court form finder:
http://hmctsformfinder.justice.gov.uk/HMCTS/FormFinder.do
The fee remission guide is EX106A.
It would then be up to a Judge. You would need an address on it (even last known) as Registry Trust won't register a CCJ without it. Even if the forms are returned as undelivered, provided the address is appropriate then you could still go for default judgment if there is no response to the claim form in the appropriate time. There is the issue of them not being at that address though a CCJ should show up on their credit record which might make they pay up.
For further info see guidance notes N1C (available from link above).
Other booklets you might find useful are the EX301 and EX202 then EX304 once the claim has been issued.
If you get a CCJ then you can go for enforcement options if not paid.
For High Court enforcement you send in a form to be signed and stamped by the County Court who will return it to you to send in to the High Court with a £60 fee. See guidance booklet EX321 for further info on enforcement. You can also download guidance booklets from the link above.
You could also pop to your local County Court to ask at the counter for further advise.