mail is instantly sent to junk

See the article Manage junk mail in Mail on iCloud.com - Apple Support

Indicate that an email is not junk

1. In Mail on iCloud.com, click the Junk folder in the Mailboxes list.
2. Select the message or messages, then do one of the following:

• • If you selected one message: click , then click Move to Inbox.
  • If you selected multiple messages: click Mark, then click “Move to Inbox”.

Subsequent messages from the same sender are no longer automatically marked as junk.

If you had created rules to move mails to junk folder change the rules Set up rules to filter email in Mail on iCloud.com - Apple Support