How do I stop the emails from going into spam?
If the automatic emails (e.g. preparation email / authorization code / activate mail etc.) are ending up in your client's spam mail, it might be due to the server or your client's email settings. Simply go to that email and unmark / report as not spam. Depending on the email / email manager, the exact steps might differ but the option can usually be found within the email itself. Unflagging that particular email will "teach" your client's email to not take any future emails as spam.
Do not attempt to keep resending the email in a short span of time as depending on the email server, the future emails may be blocked entirely. If that happens, your client needs to "report as not spam" any existing similar emails before trying again. Otherwise, you might need to send it to another email instead or change his/her email settings / contact their email server to unblock us.