I can't invite 1Password users to my Chinese branch of a Japanese company.

Hi Tomita! Thanks for letting us know about this issue that your client is seeing.

To start, I would recommend the recipients of the invitation, or the person/team that manages their email account add "@1password.com" to their safe sender list. If they're continuing to see issues after updating the safe sender list, get in touch with our team at support@1password.com and we'll be able to help dig into any specifics to resolve this. Thanks again!