The grammatical rules for spelling „e-mail-cím” has changed with the 12th edition of AkH. (Akadémiai helyesírási szabályzat), released in September 2015. It basically says that „cím” (address) must be appended to „e-mail” with a hyphen.
Here is the specific rule that applies:
https://helyesiras.mta.hu/helyesiras/default/akh12#140
Here are some articles those explain why Rule #140 applies to the spelling „e-mail-cím”:
https://helyesiras.mta.hu/helyesiras/blog/show/kijott-az-1-3-7-es-verziohttps://e-nyelv.hu/2016-09-04/e-mail-cim-e-mail-fiok/
While this new way of spelling has been around for almost a decade now, as I see its adoption is very slow: most people still use the old „e-mail cím” form, which is now incorrect. This just makes it more important to use the new spelling wherever possible.
