Send to Kindle failing due to server error

I’m in the UK and I use Send to kindle or email to get my fanfiction epubs onto my kindles (I have three kindles). I got two accepted this afternoon after a few hours of processing, I don’t know if this was by the Send to Kindle webpage or email as I tried both methods. Everything else I’m trying is failing. I’m getting an email saying it’s failed due to service error, and to try later.

Anyone seen that before? I’m just wondering if it’s something at my end, although it’s only text from word to epub via calibre, or if Amazon has a problem.