Hi All,here are the basic information,osTicket Versionv1.10.1 (9ae093d) — Up to dateWeb Server SoftwareApacheMySQL Version5.7.14PHP Version5.6.22In the last month, I have received the following error repeatedly, "Mailer ErrorUnable to email via SMTP:<server> Failed to add recipient: <receiver's email address> "
The words between <> are used just to hide real email addresses and IPs. It happens almost daily, even though not every time that I send an email. Do you have any suggestion about how to troubleshoot it and what may be the cause?Thank you in advance! (and let me know if you need more info)