Prima di mandare il messaggio, controllo il nome nella rubrica.

Because prima di is followed by an infinitive when the subject is the same in both actions.

• Prima di mandare il messaggio, controllo... = Before sending the message, I check...

The person doing both actions is the same person: I check, and I send.

If the subject changes, Italian usually uses prima che + the subjunctive:

• Controllo il nome prima che lui mandi il messaggio. = I check the name before he sends the message.

So in your sentence, prima di + infinitive is the natural choice.

Because after the preposition di in this structure, Italian uses the infinitive.

• prima di mangiare
• prima di uscire
• prima di chiamare
• prima di mandare il messaggio

So mandare means to send, and here it works like before sending or before I send.

Yes. Mandare means to send, and it is very common in everyday Italian.

With messages, both of these are possible:

• mandare un messaggio
• inviare un messaggio

In general:

• mandare is often a bit more everyday and flexible
• inviare can sound slightly more formal or technical

So this sentence is completely natural, but Prima di inviare il messaggio... would also be correct.

Italian uses articles much more often than English does.

So where English says:

• Before sending a/the message

Italian often says:

• Prima di mandare il messaggio

Even when English might leave the article out in some contexts, Italian often keeps it. Here il messaggio sounds normal and natural.

Controllo is the first person singular, present tense of controllare.

So:

• io controllo = I check

Italian often drops the subject pronoun io because the verb ending already shows who the subject is.

Conjugation of controllare in the present:

• io controllo = I check
• tu controlli = you check
• lui/lei controlla = he/she checks
• noi controlliamo = we check
• voi controllate = you all check
• loro controllano = they check

Because Italian is a pro-drop language: the subject pronoun is often omitted when it is clear from the verb ending.

• controllo already means I check
• controlli already means you check
• controlla already means he/she checks

So controllo il nome is more natural than io controllo il nome, unless you want emphasis:

• Io controllo il nome, tu controlli il numero. = I check the name, you check the number.

Here rubrica means address book or contacts list, especially on a phone.

So:

• nella rubrica = in the address book / in the contacts

This is a very common Italian word for the list of saved contacts.

Depending on context, modern Italian speakers might also say:

• nei contatti = in the contacts

But rubrica is still very common and perfectly natural.

Because nella is a contraction of:

• in + la = nella

Since rubrica is a feminine singular noun, it takes la:

• la rubrica

So:

• nella rubrica = in the address book

Other similar contractions:

• in + il = nel
• in + lo = nello
• in + i = nei
• in + gli = negli
• in + le = nelle

Yes. Il nome means the name, and in this context it most likely means the name of the person in the contact list.

So the idea is:

• Before sending the message, I check the name in the address book.

In natural English, you might sometimes say I check the contact name or I check the person’s name. Italian simply uses il nome.

Yes. Italian word order is fairly flexible.

The original sentence:

• Prima di mandare il messaggio, controllo il nome nella rubrica.

You could also say:

• Controllo il nome nella rubrica prima di mandare il messaggio.

Both are correct. The version with prima di mandare il messaggio at the beginning gives a little more emphasis to the time sequence: before sending the message.

The comma is natural when that opening phrase comes first.

Yes, controllare works very well here.

It can mean:

• to check
• to verify
• to make sure

So controllo il nome nella rubrica means something like:

• I check the name in the address book
• I verify the name in my contacts

In everyday speech, this is very natural Italian.

Yes. That is a very normal way to understand it.

Italian:

• Prima di mandare il messaggio, controllo il nome nella rubrica.

Possible English translations:

• Before sending the message, I check the name in my contacts.
• Before I send the message, I check the name in the address book.

Even though Italian uses prima di + infinitive, English may use either before sending or before I send. Both express the same idea.