Privately-owned mail service on a Synology NAS, providing multiple domain centralization management, user policy, and mail logs for easy management
Cross-platform mail solution for accessing emails on computers or mobile devices
Full-fledged security features for the defense against malicious attacks: Rspamd anti-spam mechanism, spam auto-learning, ClamAV anti-malware, and advanced SMTP security
High-availability cluster for an uptime mail service during system updates and hardware replacements via switching the mail system to the paired server in seconds
Seamless mail migration tool designed for Gmail, Google Workspace, Microsoft Exchange, Yahoo, and other IMAP servers
Specifications
Monitoring
Outgoing emails sent, resent, or unable to be sent from your Synology MailPlus Server, and incoming emails received or rejected by your Synology MailPlus Server
Real-time server information including high-availability cluster status
Statistics of various kinds of email threats presented by graphs
Statistics of blocked inbound and outbound emails respectively, along with top senders/recipients of such emails
SNMP support for monitoring mail server information including mail delivery results, security events, mail queue, IMAP/POP3/SMTP connections, and Postfix/Dovecot service statuses (SNMP MIB Guide)
Management
Multiple domain management and configuration settings related to alias, auto BCC, usage limit, and disclaimer in Synology MailPlus Server
SMTP authentication that forces clients to provide user credentials for login while connecting to Synology MailPlus Server via SMTP
SMTP settings and diverse policies for blocking emails that exceed the limits: hostname, SMTP banner, the maximum number of recipients per email, the maximum number of email hops, and the maximum size per email for Synology MailPlus Server
External postmaster, which is set to receive system emails sent to Mailer-daemon and postmaster aliases from other mail servers
Mail delivery settings that allow sending emails through other mail servers so that mail content will not be exposed to the Internet and subject to possible attacks
Synology MailPlus as a relay server that sends emails for servers listed on the trusted list, and receives emails listed on the domain list
Block and allow lists to reject, discard, or accept emails that match the set criteria
Connection policies for blocking emails from unidentifiable domains and hosts that cannot be identified or may cause Synology MailPlus Server to be overloaded
Smooth communication between Synology MailPlus Server and external mail servers/third-party clients via SMTP, POP3, and IMAP
The high-availability structure which maximizes the service uptime during system updates and hardware replacements by switching the mail system to the paired server in seconds
Mailbox quota and the corresponding notification settings for the control of data growth
Mailbox details including sizes and user statuses displayed on the console for easy management
Batch deletion of deactivated users' mailboxes to quickly free up storage space
Mail import and export:
Emails can be imported to a user's mailbox in the SMC or PST format
Users' mailboxes can be exported to PST files
Security
Custom spam filtering rules work with auto-learning to achieve accurate detection
DNSBL filters out spam published through the DNS based on a list of IP addresses of computers or networks
Greylist returns a temporary error to mail clients
Antivirus engines ClamAV and McAfee (paid option) scan all incoming and outgoing emails for viruses. When an email is found infected, the system will delete or quarantine the email and send notifications to the intended recipients
ClamAV antivirus engine databases, such as Google SafeBrowsing database or a third-party database, help detect malicious links in emails
Virus definitions are automatically updated according to the custom schedule
Various authentication mechanisms, including SPF, DKIM, DMARC, and DANE, guard against spam and identity theft
Emails with potentially dangerous elements will be filtered out when scanned by content and attachment file types
MCP (Message Content Protection) rules can filter or block targeted emails. If an email is matched with the rule's criteria, the rule score will be the total sum of the MCP score. If the total MCP score exceeds the MCP threshold score you defined, the mail system will execute the action you have selected from the following: Save to quarantine, Deliver anyway, Delete mail, Notify sender, or Forward
Auditing
Transaction logs: Provides information about sent and received emails, along with related events like spam detection, message delivery, and error notifications
Client access logs: Provides insights into user activities, including connections, email operations, and authentication processes, from the client side
Admin logs: Records setting changes made by administrators
Keyword search: Allows for the deletion and exportation of specific emails
Mail Migration
Seamless migration tools for Gmail, Google Workspace, Microsoft Exchange, Yahoo, and other IMAP servers
Supports reusing system configurations from Microsoft Exchange for a quick system replacement
Supports migrating emails from Google Workspace (Gmail) per label, with the original structure remaining intact
Multiple tasks for mail migration from external mail servers: custom filters for bypassing spam emails, emails received after a specific date, and emails exceeding the size limit (KB)
Mail migration without asking for access permissions of each source Exchange user account as long as a delegated account is available
Sizing
Maximum number of concurrent users: 4,000
Maximum number of emails processed per day: 5,721,000
Limitations
The user limit and the number of emails that can be processed per day vary for different Synology NAS models. For details, refer to the product specifications or the Synology MailPlus license page
To ensure the smooth running of security engines, it is recommended that you use models with at least 2 GB RAM
Synology MailPlus
Features
An intuitive and powerful webmail client designed for organizing emails and sharing mailboxes with work partners
User interface like three-column mode and the option for conversation view to better fit user experience
Custom filters and priority mailbox for effective mail management
Shared mailboxes to centralize emails of a specific project
A hub of communication and schedules through its seamless integration with Synology Chat and Synology Calendar
Specifications
Compose
Auto-complete list based on recipient email addresses saved in Synology Contacts
Auto-saved drafts
S/MIME and OpenPGP for email encryption and signing
Send cancellation period of 5, 10, 15, 20, or 30 seconds
User-defined text styles: font styles, font sizes, and colors
Auto-reply/forward based on user settings
Schedule send to deliver emails at a specific date and time
Mail merge for personalized mass mail (Learn more)
Mail templates to save frequently used text and images for reuse
Mail track via delivery and read receipts
Mail Management
Centralizes management with a priority mailbox collecting emails from various mailboxes or labels
Supports nested labels for hierarchical classification
Filters emails with custom exception rules for email organization
Allows sorting emails by starring, archiving, moving to customized mailboxes, as well as adding labels
Allows sharing mailboxes with internal users/groups to centralize emails over a specific project. Specific access permission to a shared mailbox can be assigned to each user/group
Allows archiving a mailbox to make all the archived emails appear in this mailbox
Provides two columns and three columns for the split pane mode, with additional layout options for two columns: one line without preview, one line with preview, and two lines
Provides a universal search bar with syntax operators to quickly find a specific email
Has flexible options for the display of external images: always display external images or ask before displaying. The latter prevents malicious senders from exploiting externally linked images
Sends push notifications with a browser extension (optional)
Displays emails in the conversation mode or the individual message mode. In the conversation mode, a single email will be grouped with all its replies
Displays mailbox usage and sends warning messages when approaching the storage limit
Supports previewing various file formats of email attachments using Universal Viewer
General Settings
Supports multiple signatures for different scenarios
Restores a conversation wrongly identified as spam
Allows adding additional SMTP servers or editing existing ones according to personal preference. For example, you can add the Google SMTP server and enter your Google account and password to send emails via your Google account in Synology MailPlus
Custom POP3 servers and predefined ones (e.g., Gmail) for fetching emails from different servers to Synology MailPlus
Administrator
Allows users to receive emails from external POP3 servers
Allows users to share links for large attachments
Allows users to use S/MIME or OpenPGP to encrypt and sign emails
Allows users to customize the logo in the Synology MailPlus web portal
Integration
Integrates with Synology Chat and Synology Calendar, serving as a hub of communication and schedules. With the plug-ins of Synology Chat and Synology Calendar, users can dive into project discussions and add emails to your to-do list right from Synology MailPlus
Adds a conversation to Synology Calendar tasks
Affiliated Utility
Synology MailPlus (Mobile)
Features
Intuitive user interface for composing mails, receiving mails, and managing mails across Android or iOS devices
Labels and user-defined mailboxes for custom mail organization
Multiple templates, various built-in stickers and emoji for a quick reply
Shared links for large attachments with local files uploaded to the home folder. To use this feature, enable shared links in MailPlus Server > Service > MailPlus Client
Synology Calendar integration within the MailPlus app for seamless viewing, managing, and filtering of calendar events
Daily summaries available for important calendar events
Option to hide or unhide calendar events
Specifications
System requirements
iOS: 16.0 or above
Android: 9 or above
System requirements for Calendar features
iOS: 16.0 or above
Android: 10 or above
Email management
Conversation view for intuitive mail browsing
Easy ways to keep mailboxes organized: apply labels, move to a certain mailbox, and mark as starred/read/unread
Localized email address to send emails with or receive emails from email addresses in native languages (e.g., Chinese and Russian)
Swipe gestures for moving across the next or previous email thread
Actions on email notifications: delete, archive, and mark as read
Undo operations for the labeled actions: delete, move, archive, and remove
Mail printing in a thread
Image viewer for viewing attached images without downloading
Manual events adding to Synology Calendar
Calendar management
Calendar view options for browsing events:
Day view
Agenda view
Calendar display options:
Show My Calendar
Show Other Calendars
Event display options:
Show hidden events
Show declined events
Actions on calendar events: view, create, edit, and delete
Event reminders sent at a specified time
Option to hide or unhide events
Notifications for all events
Daily summaries of important events
Security
Passcode lock for data protection (Touch ID supported)
OpenPGP for email encryption and decryption
Reports of suspicious emails sent to the system administrator for spam learning enhancement
Settings
Account switching to receive notifications from different sources without repeating the login process
Custom swipe options: delete, archive, mark as Spam/Not Spam, mark as read/unread, apply labels, move to a certain mailbox
Custom preview lines based on user preferences
Font size settings: large, medium, small
Push notifications when there is an email received in the user-defined mailboxes
Mobile signature settings for sender information display
Multiple templates for a quick reply
Auto remote images loading
Email content prefetching on Wi-Fi only
Integration with Synology Calendar or other calendar applications
Mailbox management: create, edit, and delete mailbox
Label management: create, edit, and delete labels
Option to enable priority mailbox with settings based on the web client
Option to open shared links directly in Synology Drive on mobile devices instead of the default browser