NAS Installation - Synology DSM 7.4

Upgrade from DSM 6.4

First upgrade to DSM 7.0 through Control Panel
Go to the Synology Download Center, Select product type and Select your Synology Product, then Select DSM version currently installed and the latest DSM version offered for this product as a target DSM version
Upload the downloaded update file in Control Panel –> Update & Restore –> Manual DSM Update and start the update
The update should run without issues, after which there are a few extensions which are obsolete and which you can uninstall

KMIP for key management

Follow the guide to install KMIP on a Synology NAS server and client
Further guidance for KMIP for key management
How to setup a KMIP Server (PyKMIP) on Debian 13

Encrypted shared folders

On a NAS where encrypting the entire /volume1 is not necessary or not advisable (no sensitive data, or performance concerns) you can encrypt single shared folders.
To avoid data in encrypted shared folders get into the wrong hands follow my guide Encrypted partitions/folders with auto-mount. This guide is outdated, but principles still apply. I will update the guide in due time.

Setup rescue login

Since DSM 7.2 and DS220+ and younger models Synology offers full volume encryption. This is finally the protection you need to fully protect all your data, including mail directories and user directories.
You need to setup the volume with encryption when you first create the volume, a non-encrypted volume cannot be encrypted in place.
The encryption keys will be stored in the Encryption Key Vault of the NAS, the keys will be automatically applied on boot of the system. This protects against theft or change of hard disks, but not against theft of the entire NAS. To protect against theft of the NAS you need to move the Encryption Key Vault to an external device running a KMIP server, which is supported by Synology. How to setup the KMIP server on a Synology NAS is described in KMIP for key management.
If you do not have another Synology NAS on another location, or you do not want to use your other NAS on another location as the KMIP server, you can install a working KMIP server on a linux machine. How this is done is described in KMIP Server (PyKMIP).
You need to take precautions in case you get locked out from your DSM because the Encrypted Key Vault is not accessible. Synology let's you login with SSH when password login is enabled even if the homes directory is not accessible (e.g. if it resides on the non-accessible encrypted volume). However, enabling password login is a security risk which I want to avoid, so I developed a method to handle this case in Rescue an encrypted volume .

Migrate MailPlus Server to new NAS

Backup full system configuration on your source NAS in Control Panel –> Backup & Restore –> Configuration Backup –> Export and save it to your local drive
Restore the configuation backup on your target NAS in Control Panel –> Backup & Restore –> Configuration Backup –> Restore, select only Users and Groups from Users, Groups, Shared Folders, Application Privileges, leave everything else unchecked
Install Hyper Backup on your source NAS
Install Hyper Backup and Hyper Backup Vault on your target NAS
Run a Hyper Backup task for application Synology MailPlus Server with your target NAS as destination
Enable rsync service on your target NAS in Control Panel –> File Services –> rsync on default port 22
Go to Control Panel –> File Services –> Advanced –> Shared Folder Sync on your source NAS, click Task List and create a manual full sync task with the (internal) IP address of your target NAS as destination
Do the sync before you intend to switch to the target NAS. Once everything else is setup, come back to Shared Folder Sync and do another full sync. The initial sync takes a while, but the follow up sync executes fast as rsync only copies files which were added or changed in the meantime.
Update all port forwards in your firewall to your target NAS
If you have a web server running on a different machine you probably keep your taget NAS behind a reverse proxy. In this case you need to update the reverse proxy settings to reach your target NAS.
Check your mail server by sending mail and receiving mail
Remove the sync task you created from your source NAS (see above) in Control Panel –> File Services –> Advanced –> Shared Folder Sync click Task List
Set the login portal for the mail client in Control Panel –> Login Portal –> Applications
Use traceroute to find connectivity issues to your mail server from another computer:
```
sudo traceroute -T -p 5001 your.mailserver.tld
```
Set up regular backups to safeguard your MailPlus data on the new NAS using Shared Folder Sync and Hyper Backup.

Create a scheduled task on your target NAS to copy renewed certificates (e.g. using Let's encrypt) if your NAS is behind a reverse proxy:

#!/bin/sh
#
# Copy certificates from web server to NAS, must be run nas root
# (c) Bernard Condrau, 2026-08-25: adapted to DSM 7.4
#
SERVER="your_webserver_generating_certificates"
PORT=22
IDENTITY="/volume1/homes/user/.ssh/id_rsa"
# make sure your user can run rsync and cksum as root without password (check visudo)
SERVER_RSYNC="sudo rsync"
SERVER_CKSUM="sudo cksum"
SERVER_CERTDIR="/etc/letsencrypt/live/cloud.condrau.com"
# CERTDIR must be hardcoded and is different in every server instance
CERTDIR="_archive/"$(sudo cat /usr/syno/etc/certificate/_archive/DEFAULT)
CERTROOTDIR="/usr/syno/etc/certificate"
PACKAGECERTROOTDIR="/usr/local/etc/certificate"

# compare cksums first to decide whether certificates need to be copied
REM_PRIV=$(ssh -i $IDENTITY -p $PORT user@$SERVER $SERVER_CKSUM $SERVER_CERTDIR/privkey.pem | cut -d' ' -f 1)
LOC_PRIV=$(cksum $CERTROOTDIR/$CERTDIR/privkey.pem | cut -d' ' -f 1)

if [[ $LOC_PRIV -ne $REM_PRIV ]]; then

	# copy certificates from web server
	sudo rsync -aPLe "ssh -i $IDENTITY -p $PORT" --rsync-path="$SERVER_RSYNC" user@$SERVER:$SERVER_CERTDIR/cert.pem $CERTROOTDIR/$CERTDIR/cert.pem
	sudo rsync -aPLe "ssh -i $IDENTITY -p $PORT" --rsync-path="$SERVER_RSYNC" user@$SERVER:$SERVER_CERTDIR/fullchain.pem $CERTROOTDIR/$CERTDIR/fullchain.pem
	sudo rsync -aPLe "ssh -i $IDENTITY -p $PORT" --rsync-path="$SERVER_RSYNC" user@$SERVER:$SERVER_CERTDIR/privkey.pem $CERTROOTDIR/$CERTDIR/privkey.pem
	sudo rsync -aPLe "ssh -i $IDENTITY -p $PORT" --rsync-path="$SERVER_RSYNC" user@$SERVER:$SERVER_CERTDIR/chain.pem $CERTROOTDIR/$CERTDIR/chain.pem

	# push the updated archive certificates to the system and restart web services
	sudo /usr/syno/bin/synow3tool --gen-all
	sudo /usr/syno/bin/synosystemctl restart nginx

	echo "certificates updated"
else
	echo "nothing to update"
fi

exit 0

Check basic TCP connectivity:

telnet [smtp_host] [port] (e.g., telnet smtp.gmail.com 587)

Check certificate assignment in Synology DSM

openssl s_client -connect mail.yourdomain.tld:465 -showcerts
openssl s_client -connect mail.yourdomain.tld:993 -showcerts
openssl s_client -connect mail.yourdomain.tld:587 -starttls smtp -showcerts

If the verify return code: 0 is not 0 but 1 or another number, your DSM most likely does not serve the intermediate certifiate. In this case you need to do the following:
1. Go to Control Panel –> Security –> Certificate –> Settings and assign Synology's default certificate to MailPlus-Server-dovcot and MailPlus-Server-postfix. Click OK and wait 30 seconds, then set the certifiates back to your Letsencrypt certificate and hit OK.
2. Go to Control Panel –> Security –> Advanced –> Custom Settings and set MailPlus-Server-dovcot and MailPlus-Server-postfix to Intermediate compatibility.
3. Stop and restart Synology MailPlus Server and Synology MailPlus (Client).
You can also enter cat /var/packages/MailPlus-Server/target/etc/main.cf | grep .pem and check whether fullchain.pem is referenced.
Re-check the certificate assignment.
Open MailPlus Server and go to Mail Delivery –> General. Enable SMTP authentication and disable external postmaster in External Postmaster.
Disable SMTP-SSL/TLS (port 465) in Synology MailPlus Server –> Service

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