Learn Hardcore Chinese: Tā yígòng fā le sān fēng yóujiàn gěi wǒ.

Very natural: 她一共给我发了三封邮件。 (Tā yígòng gěi wǒ fā le sān fēng yóujiàn.)
Also fine: 她一共发了三封邮件给我。
Less common but acceptable: 她给我一共发了三封邮件。
Avoid putting 一共 right between the verb and its object: 她发了一共三封邮件 (unnatural).

What does the 了 (le) do here? Is it past tense?

了 after 发 marks the perfective aspect (a completed event), not past tense. It tells you the sending happened and is viewed as complete. Without any time word, the sentence typically refers to a completed action (often recent).

Could I use 过 (guo) instead of 了?

Yes, but it changes the meaning:

了: a specific completed event or total within a specific frame/context.
Example: 她一共给我发了三封邮件。 (She sent me three in total [in that context].)
过: an experiential meaning (has ever done).
Example: 她给我发过三封邮件。 (She has sent me three emails at some point before.) You can combine 一共 with 过 to mean “so far in my experience”: 她一共给我发过三封邮件。

Can I put a sentence‑final 了 as well?

You can, especially with 已经 to stress a current state/result:

她已经给我发了三封邮件了。 You’ll also hear: 她已经给我发三封邮件了。 (dropping the verb‑level 了 and keeping sentence‑final 了). Both are idiomatic.

Why is the measure word 封 (fēng) used with 邮件?

封 is the standard classifier for letters and emails. Use it when counting individual emails:

三封邮件 = three emails. Other classifiers are not appropriate here. For text messages you’d use 条, for phone calls 通.

What’s the difference between 三封邮件 and 三次 (times)?

三封邮件 counts the items (three distinct emails).
三次 counts the occurrences of the action. One “time” could contain multiple emails (e.g., a batch), or one email could be sent over multiple times in rare contexts. Both are common:
- 她给我发了三封邮件。
- 她给我发了三次邮件。

Is 给 here a verb “to give,” or something else?

Here 给 (gěi) functions as a coverb/preposition introducing the recipient (“to/for”):

给我发 = send to me. It’s not the main verb in this sentence; 发 is.

Which word orders are natural with the recipient?

All of these are common:

她一共给我发了三封邮件。 (very common colloquial order)
她一共发了三封邮件给我。 (also fine)
她把三封邮件发给了我。 (uses 把, highlighting the object) They’re all grammatical; the first is the most conversational.

Is 发给 one unit? Where does 了 go in that pattern?

You can treat 发给 as a disyllabic verb (“send to”). Put 了 after the verb:

Correct: 她发给了我三封邮件。
Also correct (with the other common pattern): 她给我发了三封邮件。
Avoid: 她发给我了三封邮件。 (placing 了 after 我 is unnatural)

Why not use 送 or 寄 instead of 发?

发 (fā) / 发送: for electronic sending (emails, files, messages). Standard here.
寄 (jì): to mail physically (letters, parcels).
送 (sòng): to deliver/give in person or as a gift. For email, use 发(送). For postal letters, 寄.

Could I use 对我 instead of 给我?

No. 对 works with verbs like 说 (speak to), 笑 (smile at), 有帮助 (be helpful to), etc. For sending to someone, you want 给:

Correct: 给我发邮件
Incorrect: 对我发邮件

Can I say 她给我写了三封邮件?

Yes. 写 focuses on the writing/composition, while 发 focuses on the sending/transmission. In real life, people often say either:

她给我写了三封邮件。 (she wrote me three emails)
她给我发了三封邮件。 (she sent me three emails) If you want to be precise: she might write but not send; 发 guarantees it was sent.

How do I negate this sentence naturally?

Common options:

General past negation: 她没(有)给我发邮件。 (She didn’t send me email.)
Stress no occurrence ever (up to now): 她没(有)给我发过邮件。
Emphasize “not even one”: 她一封邮件也没给我发。

How would I ask “How many emails did she send you in total?”

她一共给你发了几封邮件？ (jǐ is used when you expect a relatively small number)
她总共给你发了多少封邮件？ (duōshao is more open‑ended)

What if I want to talk about the future or a plan rather than a completed action?

Drop the perfective 了 and add a future/intent marker:

她明天会给我发三封邮件。 (will)
她打算给我发三封邮件。 (plans to) For ongoing/habitual description, you can also use the bare form with context:
她经常给我发邮件。

Is a passive with 被 natural here?

Not really. Instead, express it from the receiver’s perspective with 收到:

我收到了她的三封邮件。 (I received three emails from her.) A 被-passive would sound odd here.

Why is 一 in 一共 pronounced yí (second tone), and how do I say 给我?

Tone sandhi:

一 becomes yí before a 4th-tone syllable (共 is 4th), so 一共 is yígòng.
给我 is two 3rd tones, so the first becomes 2nd: pronounce it géi wǒ (though it’s written gěi wǒ).

Why do we need a measure word at all? Why not say “三邮件”?

Chinese generally requires a classifier between numbers and countable nouns. The pattern is Number + Measure word + Noun:

三封邮件 (correct)
三邮件 (unnatural)

Is there any difference between 一共 and 总共 here?

They’re near-synonyms meaning in total/altogether. Both work:

她一共给我发了三封邮件。
她总共给我发了三封邮件。 Any difference is minimal; 总共 can sound slightly more colloquial in some regions, but both are widely used.