Learn Hardcore Esperanto: Kiam mi aĉetas la bileton, mi ricevas la saman retpoŝton kiel mia amikino. - When I buy the ticket, I receive the same email as my female friend.

The sentence describes what happens every time you buy the ticket (a time relationship), not a hypothetical condition. So kiam mi aĉetas la bileton = when(ever) I buy the ticket.

If you said Se mi aĉetas la bileton, mi ricevas…, that would mean something like If I (happen to) buy the ticket, then I receive…, focusing on the condition, not on the time pattern. It’s grammatically possible but changes the nuance.

Why are aĉetas and ricevas in the present tense? Could I use the future, like aĉetos / ricevos?

In Esperanto, -as (present tense) is also used for:

General truths and habits
Things that happen repeatedly

So:

Kiam mi aĉetas la bileton, mi ricevas la saman retpoŝton…
= Whenever I buy the ticket, I (always) receive the same email… (habitual action)

If you want to talk about one specific future event, you normally use the future:

Kiam mi aĉetos la bileton, mi ricevos la saman retpoŝton kiel mia amikino.
= When I buy the ticket (on that future occasion), I will receive the same email as my friend.

Both are correct; the original sentence simply describes a regular pattern.

Why do bileton and retpoŝton end in -n?

The -n marks the accusative, usually the direct object of the verb.

la bileton is the thing that is bought → direct object of aĉetas
la saman retpoŝton is the thing that is received → direct object of ricevas

Pattern:

Subject: mi
Verb: aĉetas / ricevas
Direct object: la bileton / la saman retpoŝton → add -n

So:

bileto (ticket) → bileton (ticket as direct object)
retpoŝto (email) → retpoŝton (email as direct object)

Why does saman also have -n? It’s an adjective, not a noun.

In Esperanto, adjectives agree with the nouns they describe in:

Number: -a (singular), -aj (plural)
Case: add -n in the accusative

Here:

Noun: retpoŝto → retpoŝton (direct object)
Adjective: sama → must match → saman

So you get:

la saman retpoŝton
sam- (same) + -a (adjective) + -n (accusative to match retpoŝton)

If it were plural, you’d have:

la samajn retpoŝtojn (the same emails)

What exactly does saman mean here? How is sama different from something like simila?

sama = the same (identical or effectively identical item)
simila = similar (alike, but not necessarily the same)

In the sentence:

la saman retpoŝton kiel mia amikino
= the same email as my (female) friend (gets)

This suggests it is essentially the identical email content, not just a similar email.

Examples:

Ni havas la saman libron.
We have the same book (same title, probably same edition).
Ni havas similan libron.
We have a similar book (not exactly the same one).

Why are la bileton and la saman retpoŝton using la? Could I leave the article out?

la is the definite article = the.

Here it suggests definite, known items:

la bileton → the ticket (probably a specific type or known ticket)
la saman retpoŝton → the same email (a specific email they always send)

You can drop la, but the nuance changes:

Kiam mi aĉetas bileton, mi ricevas saman retpoŝton…
Sounds more like When I buy a ticket, I receive a same-kind-of email…
This is possible, but less natural; with sama, the article is very common.

More natural variations:

Kiam mi aĉetas bileton, mi ricevas retpoŝton.
When I buy a ticket, I receive an email. (indefinite: no la)

The original with la fits a typical real-world situation: a specific automatic email everyone gets.

Why is it kiel here? What does kiel mia amikino literally mean?

kiel has several uses; here it means “as / like” in a comparison.

…la saman retpoŝton kiel mia amikino
= …the same email as my (female) friend (gets).

So, structure:

sama … kiel … = the same … as …

Compare:

Mi laboras kiel instruisto.
I work as a teacher.
Li estas tiel alta kiel mi.
He is as tall as I am.

Do not use ol here. ol is for than:

pli/grava ol = more important than

Why is it mia amikino and not mia amikinon with -n, since there is kiel before it?

mia amikino is not a direct object of a verb here, so it stays in the nominative (no -n).

Logically, the full structure is:

…la saman retpoŝton kiel mia amikino ricevas.
= …the same email as my female friend receives.

The verb ricevas is usually omitted because it would just repeat the previous verb, but it is understood. In that implied clause:

Subject: mia amikino
Verb: (implied) ricevas

Since mia amikino is the subject of that understood verb, it takes no -n.

You would only use -n if mia amikinon were a direct object of some verb, which it is not here.

Could we write the full version with the repeated verb instead of leaving it out?

Yes. A fuller, completely explicit version would be:

Kiam mi aĉetas la bileton, mi ricevas la saman retpoŝton, kiel mia amikino ricevas.

Or, even more expanded (though a bit heavy):

Kiam mi aĉetas la bileton, mi ricevas la saman retpoŝton, kiun mia amikino ricevas.

In normal, natural Esperanto, the shorter original version is preferred:

…la saman retpoŝton kiel mia amikino.

Dropping the repeated ricevas is very common when the verb is obvious from context.

How are the words retpoŝton, bileton, and amikino built?

Esperanto builds words from roots and affixes:

bileton
- Root: bilet- (ticket)
- Ending: -o (noun) → bileto (ticket)
- -n (accusative) → bileton
retpoŝton
- ret- (net, network, internet)
- poŝt- (mail)
- Together: retpoŝt- → email (internet mail)
- -o (noun) → retpoŝto
- -n (accusative) → retpoŝton
Compounds are usually written as one word in Esperanto.
amikino
- Root: amik- (friend)
- Suffix: -in- (female)
- Ending: -o (noun)
- → amikino = female friend
Without -in-, amiko is gender‑neutral in modern usage (friend of any gender), but amikino explicitly marks a female friend.

Can I change the word order, for example: Mi ricevas la saman retpoŝton, kiam mi aĉetas la bileton?

Yes. Esperanto word order is quite flexible.

Both are correct:

Kiam mi aĉetas la bileton, mi ricevas la saman retpoŝton…
Mi ricevas la saman retpoŝton, kiam mi aĉetas la bileton.

The meaning is the same. Placing the kiam‑clause at the beginning often emphasizes the time situation, but this is just a nuance.

The comma is standard to separate the clauses, especially when the kiam‑clause comes first.

How would I say this if I’m talking about one specific future event, like “When I buy the ticket tomorrow, I’ll get the same email as my friend”?

You’d normally switch both verbs to the future -os:

Kiam mi aĉetos la bileton morgaŭ, mi ricevos la saman retpoŝton kiel mia amikino.

Breakdown:

aĉetos = will buy
ricevos = will receive
morgaŭ = tomorrow (added for that “specific future time” feeling)

So:

Habit/general rule:
Kiam mi aĉetas la bileton, mi ricevas…
One specific future case:
Kiam mi aĉetos la bileton, mi ricevos…