These renewal-type letters have been around for several years but lately the letters are looking far more official and I’m sure have tricked people into sending a payment.
In my opinion the presentation and wording pertains to it being an invoice and could mislead you into thinking this is the company to whom you need to make a payment in order to renew your domain – there’s even a addressed envelope supplied!
In the vast majority of cases you should not receive a letter from your domain registrar asking for payment. You may receive a letter from Nominet https://www.nominet.uk/ (for .co.uk country-level domains) asking you to verify your details.
Please be aware when you receive any form of correspondence relating to domain name renewals. If in doubt then please feel free to contact us and we’ll look into it for you.