Service
You can manage protocols used by Synology MailPlus Server to let it communicate with external mail servers and third-party clients.
Protocol
At the Protocol tab, users can configure the SMTP settings, network interface, IMAP/POP3 settings, 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: Tick 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 domain users) that are allowed to use SMTP connection.
- Port: Assign a port for SMTP connection. The default SMTP port is 25.
- Enable SMTP-SSL: Tick 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: Tick 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. 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 a 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 connections from third-party mail clients:
- Enable POP3: Tick to allow POP3 client connections. POP3 allows users to fetch emails from Synology MailPlus Server to a mail client.
- Enable POP3 SSL/TLS: Tick to allow POP3 client connections protected with SSL/TLS.
- Enable IMAP: Tick to allow IMAP client connections. IMAP allows users to fetch emails from Synology MailPlus Server to a mail client and to manage their mailboxes.
- Enable IMAP SSL/TLS: Tick to allow IMAP client connections protected with SSL/TLS.
- Prohibit plaintext authentication over unencrypted connection: Tick to disallow plaintext authentication methods on an insecure connection. Using plaintext authentication on an insecure connection increases the vulnerability because credentials might be exposed.
- Advanced: Click Advanced 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. 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 search to help you quickly find specific messages.
- At Service > Protocol, go to the Full-Text Search section.
- Tick Enable full-text search to index all mail content for full-text search.
- To perform an accurate search for mails written in Chinese/Japanese/Korean characters, tick 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
At the MailPlus Client tab, you can configure various settings applied to all 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 allow client users to freely edit sender names on a local SMTP server.
OpenPGP
- 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 tick 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.
Shared Mailbox
- Disable the sharing feature to prevent users from sharing mailboxes: Tick to disallow users to share their mailboxes. Mailboxes that have already been shared will not be affected.
Custom Logo
- Custom Logo: Upload your image here to change the logo in the upper-left corner of the Synology MailPlus window.
- Maximum image file size: 1 MB
- Logo dimensions: The suggested logo size is 128 x 40 pixels. If the uploaded image exceeds the size, it will be proportionally compressed.