Recurring Email Errors Using Helpdesk for Email Account

Both our emails and our client (OSRAM) emails are getting “error” and “not sent” statuses in the email queue whenever there are leave applications or travel requests. When we compared the details and recipients of the email, we couldn’t find any significant issue that may have caused the emails to fail. This has been ongoing for more than a month now. We restarted the server multiple times and attempted to update the settings (SMTP Settings and port).

Whenever I try to resend the emails, I receive a “request timeout” error". As of now, our email queue is not sending emails consistently. This is the current set-up. We are not using Gmail. Whenever we use our alternate Gmail account, the emails are working consistently.