I just updated my landing page based on your feedback. Mind looking one more time?

I love the simplicity! I put minor feedback here (just 2 comments): https://screenbud.com/shot/bd49e22d-b29d-4e9a-81fe-4f554a6fb8a0

I would echo what @orliesaurus wrote below: Add some reviews / number of letters delivered / number of happy customers, etc.

Very nice! Maybe add a testimonial or two that highlight who used it and why, something like

" i wanted to send a letter to my grandad but could not be bothered to deal with the hassle of purchasing stamps and what not, the letter arrived into my grandad s hands after 4 days and he called me immediately telling me I am his favorite grandchild. Totally worth the $2"

This kind of testimony highlights, the benefits of your solution and the benefits to the end user, also it's a use-case based testimonial, win-win!