Here are a few I've used recently, that are legit and will put your order in the mail:
US-based:
Helladank Seed Company
Golden Ticket Seed Bank (these guys take Venmo and PayPal, for now, until PayPal figures it out)
Seeds Here Now (a bit high priced IMO)
Canada-based:
Hempdepot.ca (Been around since the Over Grow days)
European based:
Sannie's Shop
Attitude
Generally speaking, if it's lost in the mail or by customs, you lost your money, though Sannie will usually resend your order at least once, if that happens.