تو الان مشغول نوشتن ایمیل هستی؟

You can leave it out.

Persian often drops subject pronouns when the verb already shows the person clearly. Since هستی already means you are for singular informal you, the sentence can simply be:

الان مشغول نوشتن ایمیل هستی؟

Including تو adds emphasis, contrast, or just makes the subject extra explicit. It is not wrong at all, but it is not required.

تو is the singular informal word for you.

Use تو with:

• friends
• family members
• children
• people you know well

For a more polite or formal version, Persian uses شما:

شما الان مشغول نوشتن ایمیل هستید؟

Notice that the verb also changes from هستی to هستید.

الان means now or right now.

It tells the listener that the question is about the present moment, not a general habit. So it gives the sentence a strong currently, at this moment feeling.

Without الان, the sentence is still fine: تو مشغول نوشتن ایمیل هستی؟

But with الان, it sounds more specifically tied to what the person is doing right now.

مشغول means busy, engaged, or occupied with something.

In this sentence, it does not just mean that the person is generally busy in life. It means they are in the middle of doing the action that follows.

So مشغول نوشتن ایمیل is something like:

• busy writing an email
• occupied with writing an email
• engaged in writing an email

This construction is very common in Persian.

Because after مشغول, Persian commonly uses an infinitive / verbal noun to name the activity.

So:

• نوشتن = writing / to write
• خواندن = reading / to read
• کار کردن = working / to work

That gives structures like:

• مشغول نوشتن = busy writing
• مشغول خواندن = busy reading
• مشغول کار کردن = busy working

A different, very natural Persian way to express Are you writing an email right now? would be:

داری ایمیل می‌نویسی؟

That version focuses more directly on the ongoing action.
The version with مشغول can suggest being occupied with the action.

Yes, often there is.

In careful pronunciation, many speakers would say something close to:

مشغولِ نوشتنِ ایمیل

Those -e sounds are the ezafe linker, but in normal writing Persian usually does not write short vowels, so you often just see:

مشغول نوشتن ایمیل

A learner may not see the ezafe, but it can still be present in pronunciation.

A rough pronunciation is:

to alân mashghul-e neveshtan-e imeyl hasti?

In everyday speech, these linkers may be pronounced more lightly or reduced.

هستی is the second person singular form of بودن, meaning to be.

Here it completes the predicate:

• مشغول نوشتن ایمیل = busy writing an email
• هستی = you are

So together:

• مشغول نوشتن ایمیل هستی = you are busy writing an email

This is why the sentence ends with هستی rather than with the action itself.

Persian does not use English-style inversion or do-support.

English:

• Are you writing an email?
• Do you write emails?

Persian usually keeps the normal statement word order and turns it into a question mainly by:

• intonation in speech
• a question mark in writing

So the statement: تو الان مشغول نوشتن ایمیل هستی.

becomes the question: تو الان مشغول نوشتن ایمیل هستی؟

Same word order, different intonation and punctuation.

That is a very good question.

In a normal finite verb clause, Persian often puts the object before the verb:

ایمیل می‌نویسی
= you write / are writing an email

But here نوشتن is being used more like a noun-like action word inside the phrase مشغول نوشتن. Because of that, the structure behaves a bit differently, and ایمیل can follow نوشتن naturally:

نوشتن ایمیل
= writing an email

So this is not the same kind of structure as a simple conjugated verb clause.

Persian does not use articles the same way English does.

There is no exact equivalent of English a/an that must always be present. So ایمیل can mean:

• an email
• the email
• email

depending on context.

If you want to make it clearly an email / one email, you can say:

یک ایمیل

So you could also say:

تو الان مشغول نوشتن یک ایمیل هستی؟

That is perfectly natural too.

It is natural, but it is not the only natural option.

Two very common ways are:

تو الان مشغول نوشتن ایمیل هستی؟
This emphasizes being busy/occupied with writing.

داری ایمیل می‌نویسی؟
This is a very common way to say Are you writing an email?

The second one often feels more direct and conversational for an ongoing action.
The first one can sound slightly more focused on the person being engaged in the task.

Both are useful and common.

No, it is generally fine and natural.

That said, in very casual spoken Persian, people often simplify things:

• they may drop تو
• they may prefer داری ... می‌نویسی
• they may pronounce the linking vowels less clearly

So in everyday speech, you might hear something like:

الان داری ایمیل می‌نویسی؟

That may sound a bit more spontaneous and colloquial.
But تو الان مشغول نوشتن ایمیل هستی؟ is still a good, natural sentence.

The polite version replaces تو with شما and changes the verb accordingly:

شما الان مشغول نوشتن ایمیل هستید؟

Changes:

• تو → شما
• هستی → هستید

Everything else stays the same.

This is the version you would use with:

• strangers
• teachers
• bosses
• older people, depending on context
• formal situations