Emails to reset passwords, or verify a user’s password from email@example.com are not being received or are delayed beyond 30 minutes. Mimecast and other email filtering services are preventing a timely delivery of these emails.
Add firstname.lastname@example.org to the permitted senders list. Full details for adding permitted senders in Mimecast can be found here, but you may need to create a rule that bypasses the Greylist when the email comes from email@example.com.
The Greylist doesn’t look at the From address, it looks at the Return or Reply-To address, and the Greylist Bypass rule can only be specified for the Return or Reply To address. (This is to prevent greylisting from being bypassed by spoofing the From: field.)
As seen in the screenshot below, you will need to update the rule to bypass the Greylist when the reply-to address comes from the domain ims-email.bentley.com: