When was the airing date or year ("before 2000" or "after 2000")? Anime or Cartoon? Modern magician or Medieval? Have broom and/or modern magic hover scouter? Have the male mc has magic wand model look like antenna? Have "talking magic book" that guide them? was the school look like modern tall building from outsider look and the real appearance actually a very large castle?
https://en.wikipedia.org/wiki/Ultimate_Book_of_Spells a cartoon with a human (technomage), a witch and a half elf the show was also called UBOS
Somehow I think I remember something like that, but it may be a mix-up with something else. Still, the fact that it's a magical academy does make me think of anime, but the formula MC+clever girl+best bud sounds very western.
Dude said 15 years, the animrs that i think of is maburaho and rosario vampire. Maybe OP didnt remember the settings well, alice academy is also one but not that fit to description. Hapiness Witch craftwork. Im really curious now. You sure this isnt twilight right?
1965? http://tvtropes.org/pmwiki/pmwiki.php/Anime/JackAndTheWitch is the only thing i can find that vaguely matches
Go to an anime database such as anime-planet.com and chose to sort out the anime by date then go to 2-3 years after you watched just to be safe and work your way back.