Invitation envelope help!

I posted yesterday about how to write and guest. Now I have another question:

When you are addressing the invite to a couple who don't live together, websites say don't put both names on the outer envelopes. However, I want to. I'm not using inner envelopes so I need to put both names on the outer envelope. How should it look:

Mr. John Smith and Ms. Jane Doe

or

Mr. John Smith
Ms. Jane Doe

TIA!

I did the second one.

HTH

I thought so! Thats how I did it for my Save the dates. Thanks ladies!!