I filed extensions for two LLCs and received confirmation that they had been approved. But the confirmations don't include the NAMES of the LLCs so how can I prove it?

Check the EIN on each confirmation. Click here to check your extension e-file status.

Sorry - I should have mentioned that  there were no  EIN numbers on them either. There was NOTHING in either email to identify to which LLC the message applied.

I should also add that I ended up spending almost two hours on the phone with someone from Intuit either and THEY couldn't find the info either. They eventually found "submission IDs" which they sent me but those are meaningless at my end.

You have the EIN's for your LLC's. Click on my link, check your extension e-file status, enter the LLC EIN and see if it was filed and accepted or rejected.

If these are partnership LLC's, that is Form 7004 and must be mailed in. It's too late for Form 1065 Partnership since the return was due March 15, 2019.

I guess I'm still not explaining properly --- I got a penalty letter from the IRS claiming that the extensions had not been filed --- in other words, they have no record of the extensions. So the ONLY evidence I have that I actually filed extensions are these emails from Intuit but because they don't have explicit LLC info in them, they're useless as prrof.

See my other comments.

What form did you file? 7004 or 4868? Are you a Single member LLC or Partnership LLC?  <a rel="nofollow" target="_blank" href="https://www.irs.gov/businesses/small-businesses-self-employed/penalty-relief-due-to-first-time-penalty-abatement-or-other-administrative-waiver">https://www.irs.gov/businesses/small-businesses-self-employed/penalty-relief-due-to-first-time-penalty-abatement-or-other-administrative-waiver</a>