Μόλις τελειώσει η δεξίωση, ο φωτογράφος θα μας στείλει όλες τις φωτογραφίες από τη φωτογράφιση.

Here μόλις means as soon as.

That is a very common learner trap, because μόλις can also mean just in other sentences, as in I just arrived. In this sentence, though, it introduces a time clause:

Μόλις τελειώσει η δεξίωση = As soon as the reception is over / ends

So the meaning is about timing, not about something happening just now.

Because Greek is focusing on the action as a completed whole.

τελειώσει is the perfective non-past form of τελειώνω. Many learner materials describe this as the form used in the subjunctive. After μόλις, Greek normally uses this form when it means as soon as something is completed.

So:

• μόλις τελειώσει = as soon as it finishes
• not μόλις τελειώνει, which would not be the normal choice here

The idea is not while it is ending, but once it has ended.

Because μόλις can trigger this verb form by itself.

In many Greek structures, the perfective non-past form appears with να, but not always. After certain words such as μόλις, όταν, and some other conjunctions, Greek can use this dependent form without να.

So:

• μόλις τελειώσει = correct
• μόλις να τελειώσει = not correct here

Because in Greek, time clauses introduced by words like μόλις usually do not take θα, even when they refer to the future.

English often says:

• As soon as the reception ends...

Greek works similarly in this respect: the future meaning is understood from the whole sentence, so Greek says:

• Μόλις τελειώσει η δεξίωση...

not

• Μόλις θα τελειώσει η δεξίωση...

The θα appears in the main clause:

• ο φωτογράφος θα μας στείλει...

Η δεξίωση is the subject of τελειώσει.

It is in the nominative case, which is the normal case for the subject of a verb.

So literally, that part is:

• the reception finishes/ends

Even though English often uses the reception ends, Greek also makes the reception the subject in exactly the same way.

Because the sentence begins with a subordinate time clause:

Μόλις τελειώσει η δεξίωση, ...

In standard Greek writing, when this kind of introductory clause comes first, it is very normal to separate it from the main clause with a comma.

So the comma marks the boundary between:

• the time clause: Μόλις τελειώσει η δεξίωση
• the main clause: ο φωτογράφος θα μας στείλει...

Θα στείλει is the normal Greek way to say will send.

Greek does not have a separate future ending like some languages do. Instead, it commonly forms the future with:

θα + verb form

Here, στείλει is the perfective non-past form of στέλνω, and with θα it gives the simple future:

• θα στείλει = he will send

The perfective form is used because this is a single complete action: one act of sending.

Because μας is a weak object pronoun, often called a clitic, and in Greek these usually come before the finite verb.

So Greek says:

• θα μας στείλει

not normally:

• θα στείλει μας

Here μας means to us.

That is another thing English speakers often notice: Greek does not need a separate word like to here. The pronoun itself shows the indirect object.

It can mean different things in different contexts, but here it means to us.

Compare:

• μας στείλει = sends us / to us
• οι φωτογραφίες μας = our photos

So the form is the same, but the role changes depending on the sentence. In this sentence, because it appears before the verb as an object pronoun, the meaning is to us.

Because όλες has to agree with φωτογραφίες in gender, number, and case.

φωτογραφίες is:

• feminine
• plural
• accusative

So όλες must also be feminine plural accusative.

Also, the article τις is there because we mean a specific set: all the photos.

So:

• όλες τις φωτογραφίες = all the photos

A useful comparison:

• όλες οι φωτογραφίες = all the photos, when it is the subject
• όλες τις φωτογραφίες = all the photos, when it is the object

They are related, but they are not the same thing.

• φωτογραφίες = photos / photographs
• φωτογράφιση = photo shoot / photography session

So the sentence is talking about the photos that came from that photo shoot.

This is a nice example of Greek using one noun for the results and another for the event/process.

Because από means from, and after από Greek uses the accusative case.

So:

• από τη φωτογράφιση = from the photo shoot

Here τη φωτογράφιση is accusative singular feminine.

This is different from a genitive structure such as:

• οι φωτογραφίες της φωτογράφισης = the photos of the photo shoot

Both can make sense, but they are different structures. In your sentence, από emphasizes origin: the photos came from that session.

Both relate to the same article form, but in normal spelling and pronunciation the final -ν is often dropped before certain consonants.

So:

• τη φωτογράφιση is completely normal
• την φωτογράφιση may also appear, but τη is the usual form here

Before φ, dropping the final -ν is very common.

Yes. Greek word order is more flexible than English word order.

This sentence starts with the time clause first, which is very natural:

• Μόλις τελειώσει η δεξίωση, ο φωτογράφος θα μας στείλει όλες τις φωτογραφίες από τη φωτογράφιση.

But you could also put the main clause first:

• Ο φωτογράφος θα μας στείλει όλες τις φωτογραφίες από τη φωτογράφιση μόλις τελειώσει η δεξίωση.

Both are natural. The version with μόλις first gives a little more emphasis to the timing.