Email alerts are not sent

Hi OpenSearch community.

I have run in to the following problem where alerts are being successfully generated but I’m not getting any email notifications.
Can confirm that email as a destination, senders et was set up as per documentation, and email addresses for sender and recipients are correct and working as using same addresses in Wazuh alert notifications.
When testing the email alert I get the following error:
javax.mail.MessagingException: Invalid Addresses
Screenshot 2022-11-30 220010

Am I missing something in the setup? any help would be greatly appreciated.