Az értesítési cím helyes.

Both a and az mean the in Hungarian. Which one you use depends on the sound that follows:

• a before a consonant sound
• az before a vowel sound

Since értesítési begins with é, the correct form is az.

So:

• az értesítési cím
• but a helyes cím

Értesítési is an adjective meaning something like notification-related or for notification.

It comes from the noun értesítés = notification / notice, plus the suffix -i, which often turns a noun into an adjective meaning related to, belonging to, or used for.

So:

• értesítés = notification
• értesítési = notification-related / for notification

In értesítési cím, this adjective describes what kind of address it is.

In Hungarian, adjectives normally come before the noun they describe, just like in English.

So:

• helyes cím = correct address
• értesítési cím = notification address

That means értesítési must come before cím.

In Hungarian, the verb to be is usually left out in the present tense, third person, when one noun or adjective is being equated with another.

So English says:

• The notification address is correct.

But Hungarian says:

• Az értesítési cím helyes.

No van is needed here.

Compare:

• A cím helyes. = The address is correct.
• A cím új. = The address is new.

However, in other tenses or persons, a form of to be does appear:

• A cím helyes volt. = The address was correct.
• A cím helyes lesz. = The address will be correct.
• Én fáradt vagyok. = I am tired.

Helyes is an adjective meaning correct. In this sentence, it works as a predicate adjective: it tells you something about the subject.

Structure:

• Az értesítési cím = the notification address
• helyes = correct

So the sentence literally works like:

• The notification address — correct.

The missing is is understood.

No. Cím is in the basic dictionary form, the nominative.

That is because it is part of the subject:

• Az értesítési cím = the notification address

There is no case ending because nothing in the sentence requires one.

If the word had another role, it might take a suffix:

• címet = address (object)
• címen = on the address / under the title
• címre = to the address

But here it stays simply cím.

Yes. Hungarian word order is flexible, and changing it can change the focus or emphasis.

The neutral version is:

• Az értesítési cím helyes.

You could also say:

• Helyes az értesítési cím.

This still means the same basic thing, but it puts more emphasis on helyes = correct.

So the original version is the most straightforward, neutral statement.

It is a fixed expression, but grammatically it is best understood as an adjective + noun structure:

• értesítési = adjectival form
• cím = address

Hungarian often expresses ideas that English might show with of, a noun-noun combination, or a hyphen by turning one part into an adjective with -i.

So instead of a structure like notification’s address, Hungarian uses:

• értesítési cím

This is very common in formal or administrative language.

A rough pronunciation guide is:

• ér-te-shí-té-shi

A few useful points:

• é is a long vowel, roughly like ay in say, but cleaner and longer
• í is a long ee sound
• s in Hungarian sounds like English sh
• sz would be the normal English s sound, but that letter combination does not appear here

So:

• értesítési has two sh sounds because of the two s letters
• cím sounds roughly like tseem, because Hungarian c is pronounced ts

Yes. Helyes can mean correct, proper, right, or appropriate, depending on context.

For example:

• Ez helyes. = This is correct.
• Helyes válasz. = Correct answer.
• Nem helyes így beszélni. = It is not proper to speak like that.

In your sentence, the intended meaning is the straightforward one: the address is correct.

Normally, no: in standard present-tense third-person sentences like this, Hungarian leaves van out.

So:

• Az értesítési cím helyes. is correct.
• Az értesítési cím van helyes. is not normal Hungarian.

But van can appear in other sentence types, for example to express existence or location:

• Itt van a cím. = The address is here.
• Van egy címem. = I have an address. / There is an address I have.

So the absence of van in your original sentence is completely normal.