Contact
One address, and a person reads it.
Missing a name
This is the most useful thing you can send. If a name isn't on the site, or your family spells it a way that isn't here, write and it goes on the list to be researched and added.
Something's wrong
A meaning that isn't right, an origin that's off, a famous bearer who never existed — these matter, and a correction is genuinely welcome. If you know the source, send that too; it makes the fix quicker and more certain.
Broken links, a page that won't load, or anything that's simply annoying to use: also worth an email.
An order, a delivery, a refund
These are not yourname's to fix, and writing here will only slow you down.
yourname doesn't sell the products. Clicking a card takes you to a shop — Zazzle, or another merchant — and they take the payment, print the item and post it. They are the ones who can find your order, change it, chase it or refund it. Your confirmation email came from them, and that is the thread to reply to.
What is worth telling yourname: if a product link sent you somewhere unexpected, or a preview showed a name differently from how it arrived. That is a fault on this side.
Merchants and press
If you make personalised goods and want them considered for the site, or you're writing about it and need something, use the same address and say so in the subject line.
Elsewhere
There's a short video for a name most days on Instagram, at @yourname.thankful.day. Messages there are read as well, though email is more reliable.