After receiving the offer, I signed the reply email. If I don't go to work, it won't have much impact under normal circumstances, but I will be added to the recruitment blacklist of this company, which means I can't enter this company for at least a while.

Employment invitation is an invitation to conclude a contract, which has certain legal effect. For example, if the new employer refuses to accept you after receiving the invitation and gives a positive reply, and submits his resignation to the original employer, you can claim compensation for the loss. Similarly, if you don't join the company after giving a positive answer, the other company can also hold you accountable. The legal effect of employment invitation has little to do with whether it is in the form of e-mail or paper. In addition, there is usually a reply time agreement in the invitation letter.