Some mail client - Apple Mail in particular, and Veeam Backup Server notification services in my experience - do not recognize when a new Let's Encrypt SSL certificate is installed on the Axigen server until the email services (SMTP and IMAP) are manually restarted on the Axigen server. They seem to be handed the previous SSL certificate by the Axigen server, or perhaps hold onto a cached one. Either way, if a simple/quick/automatic restart of the mail services would be performed on the Axigen server when a new Let's Encrypt SSL certificate is installed, this would avoid having to log into the Axigen webadmin and manually performing this task when we start receiving notices from our clients that their Apple mail clients are complaining the server cannot be trusted.