429 Too Many Requests from zerossl.com

I've just installed a fresh VPS with traefik and I have about 30 domains to generate SSL certs.

The problem is that traefik tries to generate all certs at once and zerossl.com sends 429 Too Many Requests even before first certificate is being confirmed.

In result, I have no certs. Is it possible to set some delay between requests?

Sounds like a reasonable feature request for Traefik Github.