Service
You can manage popular mail protocols used by Synology MailPlus Server to let it communicate with external mail servers and third-party clients.
Protocol
In the Protocol page, users can configure the settings of SMTP, network interface, IMAP/POP3, and full-text search function.
SMTP
Synology MailPlus Server uses SMTP to communicate with mail servers and third-party mail clients.
- At Service > Protocol, go to the SMTP section.
- Enable the following SMTP-related protocols:
- Enable SMTP: Select to allow mail servers/clients to communicate with Synology MailPlus Server via SMTP.
- Account type: Select the source of user accounts (i.e., local users, LDAP users, or Windows AD domain users) that are allowed to build up SMTP connection.
- Port: Assign a port for SMTP connection. The default SMTP port is 25.
- Enable SMTP-SSL: Select to allow mail servers/clients to communicate with Synology MailPlus Server via SSL-protected SMTP. You can assign a port for SMTP-SSL connection.
- Enable SMTP-TLS: Select to allow mail servers/clients to communicate with Synology Mailplus Server via TLS-protected SMTP. You can assign a port for SMTP-TLS connection.
- Click Apply to save the settings.
Note:
- If you have enabled SMTP-TLS in Synology MailPlus Server and set the TLS/SSL Profile Level to Modern compatibility at Control Panel > Security > Advanced, some mail clients (e.g., Outlook 2016) may be unable to establish connections owing to this setting. To ensure better compatibility with mail clients, please change the TLS/SSL Profile Level to Intermediate compatibility.
Network Interface
You can bind the SMTP, POP3, and IMAP services to one network interface.
- At Service > Protocol, go to the Network Interface section.
- In the Network Interface menu, select the desired interface.
- Click Apply to save the setting.
IMAP/POP3
Synology MailPlus Server uses IMAP and POP3 to communicate with popular third-party mail clients (e.g., Apple Mail and Microsoft Outlook).
- At Service > Protocol, go to the IMAP/POP3 section.
- Enable the following mail protocols to allow POP3/IMAP connection from third-party mail clients:
- Enable POP3: Select to allow POP3 client connection. POP3 allows users to fetch emails from Synology MailPlus Server to a mail client.
- Enable POP3 SSL/TLS: Select to allow POP3 client connection protected with SSL/TLS.
- Enable IMAP: Select to allow IMAP client connection. IMAP allows users to fetch emails from Synology MailPlus Server to a mail client and manage their mailboxes.
- Enable IMAP SSL/TLS: Select to allow IMAP client connection protected with SSL/TLS.
- Prohibit plaintext authentication over unencrypted connection: Select to disallow plaintext authentication methods on an insecure connection. Using plaintext authentication increases the vulnerability because the credentials might be exposed especially on an insecure connection.
- Advanced: Click the Advanced button to set the maximum IMAP connection per user from the same IP address at the same time. The maximum number is 5,000. Click OK to save the changes.
- Click Apply to save the settings.
Note:
- If you have enabled POP3 SSL/TLS or IMAP SSL/TLS in Synology MailPlus Server and set the TLS/SSL Profile Level to Modern compatibility at Control Panel > Security > Advanced, some mail clients (e.g., Outlook 2016) may be unable to establish connections owing to this setting. To ensure better compatibility with mail clients, please change the TLS/SSL Profile Level to Intermediate compatibility.
Full-Text Search
The system can index all users' mail content and provide a thorough email search to find specific messages fast and accurately.
- At Service > Protocol, go to the Full-Text Search section.
- Select Enable full-text search to index all mail content for full-text search.
- To have an accurate search in mails written in Chinese/Japanese/Korean characters, select Allow character search for Chinese, Japanese, and Korean mail.
- Click Apply to save the settings.
Note:
- Enabling the full-text search requires more system resources.
MailPlus Client
In the MailPlus Client page, you can configure various settings for all the client users.
POP3
- Allow users to receive email from external POP3 servers: Tick to allow users to fetch external emails to Synology MailPlus via POP3. You can specify the receiving interval in minutes.
SMTP
- Allow users to change the sender name on the local SMTP server: Tick to enable client users to configure the sender names at their will on a local SMTP server.
OpenPGP
- Disable OpenPGP for all users: Tick to disable OpenPGP for all users.
Shared Link
- Allow users to create shared links for large attachments: Tick to automatically turn large attachments into shared links to reduce mail size for smooth delivery. The following Control Panel settings should also be adjusted:
- Go to User > Advanced > User Home and select Enable user home service to create home folders for all users. Large attachments will be uploaded to the user's home folder.
- To allow users to create or delete shared links, go to Privileges to allow all users to use File Station.
Custom Logo
- Custom Logo: Upload your image here to change the Synology MailPlus logo in the upper-left corner of the window.
- Maximum image file size: 1MB
- Logo dimensions: The suggested logo size is 128 x 40 pixels. If the uploaded image exceeds the size, it will be proportionally compressed.