Learn French: Elle cherche une adresse dans cet e-mail. - She is looking for an address in this email.

In French, the verb chercher already means "to look for" all by itself. You do not need to add a word like pour after it. So, Elle cherche une adresse translates directly to "She is looking for an address".

Why is it cet e-mail instead of ce e-mail?

The word for "this" before a masculine noun is usually ce. However, because e-mail starts with a vowel sound, ce changes to cet to make it easier to pronounce. If the word were feminine, it would be cette.

Is adresse feminine, and why does it only have one "d"?

Yes, adresse is feminine, which is why we use une. Notice that the French word is spelled with only one "d", unlike the English word which has two! This is a very common spelling mistake for English speakers.

The translation says "She is looking", but does cherche just mean "She looks"?

French does not have a separate "is doing" tense. Elle cherche can mean either "She looks" or "She is looking" depending on what makes sense. Here, it means she is actively searching right now.