Hi @Joselyn Martinez, the login code comes from an Atlassian sender (noreply...@am.atlassian.com), so the first thing to rule out is their spam folder and any filtering on their side. If they're on a company domain this is very often the mail gateway quietly dropping it, so their IT would need to allow am.atlassian.com and id.atlassian.com; on Gmail or Outlook, adding noreply@id.atlassian.com as a contact is usually enough. Trello lists every sending domain to allowlist here: Not receiving confirmation or password reset emails
To get them working in the meantime, that code isn't the only way in. If their Trello email is a Google, Microsoft or Apple address, "Continue with Google" and the like on the login screen skips the email step entirely. And since they're on your team, you can resend their invite from your members list, which gives them a fresh confirmation link.
If none of that lands and test emails reach them fine, the usual culprit is that their address is sitting on Atlassian's suppression list after an earlier bounce. Neither of you can clear that, only Atlassian can, and it's quick once they do. That's the point to contact Trello support, and it's worth raising from your own account so the login barrier doesn't get in the way of asking.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.