Technical Tip : KB – FortiMail Server Mode NAS down behavior

This article describes the behaviour of FortiMail operating in server mode when the connectivity to NAS/NFS server is down

1. As the mailbox is stored in NAS, if the NAS is down, FortiMail will switch to use its local disk storage to store the emails. The switch happens immediately and there are no timers to control the interval of the switch
2. Depending on the type of protocols the email client is using when communicating with FortiMail, the behaviour will differ
3. If the email client is using the IMAP protocol, the email data will be deleted when it tries to sync the emails. Emails sent/received during this time period will be stored on a local disk, and it will be synced back to NAS when it is back online
4. If the email client is using the POP3 protocol, the mail client downloads the email to the user’s computer, a copy of the email usually does not remain on the email server, and therefore, the emails can only be viewed from that user’s computer unless the clients are configured to leave copies of email on the mail server
5. Mail data/quarantine emails will be stored locally until NAS is restored, this could have an impact on an increase of the maildisk size on the local disk unless the emails/quarantine are manually deleted