Each ad clues a fictional object or place. The first number in the reply-to address gives the enumeration for the name of the object. Indexing into the name by the second number spells out MALE OWNER OF 4 PRIVET DRIVE. Thus, the answer is VERNON DURSLEY. The clued objects are:
1. (M)irari 2. Orb of (A)ldur 3. Cal(l)andor 4. Gl(e)ipnir 5. Am(o)racchius 6. (W)interfell 7. Sti(n)g 8. Al(e)thiometer 9. Castle (R)oogna 10. Book of Th(o)th 11. Goblet of (F)ire 12. HK-(4)7 13. (P)ern 14. Sword of Shanna(r)a 15. R(i)ngworld 16. A(v)alon 17. Scon(e) of Stone 18. Ba(t)tle School 19. SSV Norman(d)y 20. Naxx(r)amas 21. Arrak(i)s 22. (V)orpal Sword 23. Gold(e)n Fleece