As per Feature Request: Provide an option to allowlist email addresses to prevent mail from them from being discarded as invalid under Service Desk settings it was implemented in JSM 5.5.0, but, customers want to have ability to allow individual e-mail addresses.
According to our documentation they can't add individual email addresses to it: Managing the allowlist and blocklist which I quote:

The allowlist does not support individual email addresses, wildcards, or pattern matching.

They need an option, under the above feature, to whitelist certain email addresses so Jira can process them.
Thanks