You are right. You cannot onboard a new job before you leave your old one. Accepting an offer is not part of the onboarding process though. It happens before.

After an interview process the company makes an offer. The candidate can then accept or reject it. But that is really all informal. You can then negotiate with them for an official start date and contract. You just need to ensure you can hand in your notice and work the rest of your notice period before the start date of your new contract.

I don't know anyone that would hand in their notice before accepting the initial offer of a company. At least here in the UK.

[–] neatchee@piefed.social 0 points 23 hours ago (1 children)

Communicating with IT is absolutely part of the onboarding process. And the phrasing of the email clearly states they are rescinding an offer acceptance, as in they had already accepted and begun onboarding.

[–] nous@programming.dev 2 points 22 hours ago

You are not considered to be working somewhere until you have signed a contract and after the start date on that contract. Accepting a offer is not signing a contract. You are not working at the new place yet. You have no obligations to do anything at that point. You just need to have stopped working at your current employment before your start date. You definitely do not need to quit before accepting the offer. No where I have worked requires that.