Whenever an email contains an illegal character or there is something wrong with the email formatting, Jira will throw an error like the following: Could not parse message recipients.
javax.mail.internet.AddressException: Domain contains illegal character in string ``'email address''' and will simply reject the email.

The suggestion is to improve the handling for these email by using a default reporter to process the email and add a message indicating there was a problem, adding the available information so the agent can have a better idea of what happened and who to reach out to.

Workaround: use a third party add-on like Jira Enterprise Mail Handler or Email this issue which seem to have options to deal with these scenarios.