Appointment is deleted

[iknl1]

I have a strange issue.

When an appointment is booked, without a validation step there is send a confirmation e-mail. This e-mail is send to a corporate mail address. The e-mail doesn’t arrive, the appointment disappears in the calendar.

When a appointment is booked, with a validation step there is send a validation e-mail. This e-mail is send to a corporate mail address. The e-mail is received in unwanted items. When clicked on the validation link there is an error. After a while the appointment disappears in the calendar. Could safelink protection be the problem?

The appointment app is working when an private e-mail address is used (for example outlook.com). In both the situations, with and without the validation step.

What am I doing wrong?

[SergeyMosin]

Could safelink protection be the problem?

I am not sure what the safelink protection is, but it does sound like it might be a problem if it:

1. follows the "Confirm/Cancel" links in the email and then
2. clicks the actual button the "confirm action" page.

I know some anti-virus programs do "step 1" above, but I have never heard of email/anti-virus software that does the "step 2"