Enclosed is for a letter or package; not really for emails. Other than that, I like please find attached. it is accurate and not really too informal/formal.

Hi Emarbe, the choice that suits well in that context is to use the verb attach when you are sending a file via e-mail. Greetings from Argentina.

'Enclosed' would be if you were sending it as a letter. The document would be 'enclosed' in the envelope. It doesn't work for things you're sending by email. As you seem to already know, the verb to use is 'attach.' Please find my certificate attached. Please find my certificate in the attachment. Or simply: My certificate is attached.