![Synology MailPlus Server Licensing Explained [2026 Guide]](https://univik.com/cdn/blog/synology-mailplus-server-licensing.webp)
MailPlus Server licences are perpetual you pay once and they do not expire. The first 5 users are included free on qualifying Synology NAS models. Additional users require per-user licence packs purchased from Synology (in packs of 5, 20 or more). Licences are transferable to replacement hardware through the Synology account. A shared mailbox like info@company.com counts as a licenced user if it is a standalone mailbox not if it is an alias forwarding to another account. Deactivating a user does not free their licence slot; deleting the account does. Email data is not deleted if licences are removed, but delivery and access stop.
The Perpetual Licence Model: Pay Once, Own It
MailPlus Server does not use a subscription model. There are no monthly fees, no annual renewals and no per-user charges recurring over time. Licences are purchased once and remain valid indefinitely.
This distinguishes MailPlus Server from both Microsoft 365 and Google Workspace, which charge a monthly or annual per-user fee that recurs for as long as the service is used. A MailPlus Server licence purchased today is still valid in five years no renewals, no price increases on existing licences.
The trade-off is the same one that applies to any perpetual licence: you own what you bought. Synology continues developing MailPlus Server and releasing new versions. Licence packs are per-seat counts, not version-specific. When MailPlus Server upgrades from 3.x to 4.x, your existing seat licences continue to apply without any repurchase. You own the seats; Synology manages the software version.
The Free Tier: 5 Users at No Cost
MailPlus Server includes 5 free user licences on qualifying Synology NAS models. These are not trial licences they do not expire and do not require any purchase. Organisations with 5 or fewer users can run MailPlus Server permanently at no licence cost.
Qualifying NAS models. The free 5-user licence applies to most current and recent Synology NAS models running DSM 7. Lower-end entry models (the J series) have historically had restrictions on MailPlus Server capability, so check the MailPlus Server compatibility list at synology.com before purchasing hardware for a MailPlus Server deployment.
The free licences are already activated after installation. Install MailPlus Server from Package Center and the 5 free licences are available immediately no registration or activation code required. Add user accounts up to 5 and they are covered.
Adding a 6th user requires a purchased licence pack. The moment you need a 6th mailbox, you need to purchase additional licences. There is no per-user purchasing licences are sold in packs. The smallest pack is 5 users.
What Counts as a Licenced User
Each active mailbox in MailPlus Server occupies one user licence. A user licence is consumed when a user account is created and has an assigned mailbox regardless of whether that user logs in frequently or at all.
A 20-person organisation running MailPlus Server needs 20 user licences (15 purchased beyond the free 5) if each person has their own mailbox. There is no volume discount built into the base licence model and no distinction between heavy users and occasional users.
The Shared Mailbox Question
This is the question that causes the most confusion in MailPlus Server licence planning and Synology’s own documentation does not address it clearly.
A shared mailbox like info@company.com or support@company.com can be implemented two ways in MailPlus Server and the licence implication differs:
Shared mailbox as a standalone account: counts as a licence
- A user account is created for info@company.com
- Multiple team members log in with shared credentials
- The account has its own mailbox, sent folder and storage
- Consumes one licence slot
Shared address as an alias: does NOT consume a licence
- info@company.com is created as an alias in MailPlus Server
- Email sent to info@ is forwarded to one or more individual accounts
- No standalone mailbox exists for the alias
- Does NOT consume a licence slot
For small teams where two or three people share a support inbox, an alias forwarding to a group is licence-efficient and avoids creating a shared login. For teams that need a shared sent folder and shared email history (where it matters who responded to what), a standalone shared account is necessary and consumes a licence.
Buying Additional Licences
Synology sells MailPlus Server licences through the Synology Web Store and authorised resellers. Current licence pack sizes and approximate prices:
| Licence Pack | Users Added | Approximate Price |
|---|---|---|
| MailPlus 5 Licence Pack | +5 users | ~$120–130 one-time |
| MailPlus 20 Licence Pack | +20 users | ~$400–450 one-time |
| MailPlus 100 Licence Pack | +100 users | ~$1,800–2,000 one-time |
Check current prices at synology.com
Licence prices change over time and vary by region. The figures above are approximate as of mid-2026. Always check the current prices in the Synology Web Store for your region before budgeting. Reseller pricing may differ from the Web Store price.
After purchasing, licences are added to your Synology account. In DSM, open MailPlus Server then go to the licence section and activate the purchased licences from your account. Licences are active immediately after activation no restart required.
Licence Portability: Moving to New Hardware
MailPlus Server licences are tied to the Synology account, not to a specific NAS device. When replacing the NAS hardware, licences transfer with the account migration.
When replacing NAS hardware: migrate MailPlus Server to the new NAS using the migration wizard or a fresh install. After migration, the licences re-activate automatically when MailPlus Server connects to the Synology account on the new hardware. No separate licence transfer process is required the account association handles it.
If the old NAS failed unexpectedly: install MailPlus Server on the replacement NAS and log in with the same Synology account. The licences are available from the account even if the old NAS is no longer operational. Contact Synology support if licences do not activate automatically after a hardware failure replacement.
Licence portability is one of the practical advantages of the perpetual model for organisations that replace hardware on a 4 to 5 year cycle. Each hardware refresh does not require a new licence purchase the existing licences travel with the account.
Deactivated Accounts and Licence Slots
A common misconception: deactivating a user account frees up the licence slot. It does not.
Deactivating an account blocks login access but keeps the mailbox intact and the licence occupied. The user cannot receive new email, but the account still counts toward the licence total. To free the licence slot for a new user, the old account must be deleted not just deactivated.
For organisations managing offboarding, this has a practical implication:
Export the mailbox before deleting. Once a MailPlus Server account is deleted, all email is permanently removed. Export the mailbox (PST on DSM 7, MBOX on DSM 6) and convert to an archive format before deleting. See our guide to exporting deactivated accounts for the full process.
Delete the account when the archive is confirmed. Only after verifying the archive is complete and correctly converted should the account be deleted and the licence slot freed.
What Happens to Email If Licences Are Removed
If licences are removed or expire which does not happen under normal operation since licences are perpetual, but could occur if a licence is revoked MailPlus Server handles it as follows:
Email data is not deleted. Existing email in user mailboxes remains on the NAS. Removal of licences does not trigger any email deletion.
New email delivery stops for over-licence accounts. If the number of active accounts exceeds the available licences, MailPlus Server may prevent new email delivery for the excess accounts. The mailboxes exist but incoming email is rejected.
Historical email remains accessible via export. Even if MailPlus Server stops delivering email, existing mailbox data can still be exported as PST files on DSM 7 or MBOX files on DSM 6 and converted via Univik Synology MailPlus Converter for archiving or migration. Access to historical email does not depend on having active licence coverage.
Licence Cost vs Cloud Email
The comparison organisations most often make is between MailPlus Server licences and Microsoft 365 or Google Workspace per-user monthly fees. The comparison favours MailPlus Server over a multi-year horizon but depends heavily on user count and hardware already in place.
| MailPlus Server (20 users) | Microsoft 365 Business Basic (20 users) | Google Workspace Business Starter (20 users) | |
|---|---|---|---|
| Year 1 email cost | ~$450 one-time (15 purchased + 5 free) | ~$1,440/year ($6/user/month) | ~$1,440/year ($6/user/month) |
| Year 3 email cost (cumulative) | ~$450 (same no renewal) | ~$4,320 | ~$4,320 |
| Year 5 email cost (cumulative) | ~$450 | ~$7,200 | ~$7,200 |
| NAS hardware required | Yes capital cost not included | No | No |
| IT administration required | Yes ongoing | Minimal | Minimal |
| Uptime guarantee | Dependent on hardware and power | 99.9% SLA | 99.9% SLA |
The licence cost comparison favours MailPlus Server significantly over multi-year horizons but the full picture includes NAS hardware cost and IT administration time. For organisations that already have a Synology NAS for file storage, MailPlus Server adds email hosting at marginal additional cost. For organisations without a NAS, the hardware acquisition changes the cost equation.
Frequently Asked Questions
Do MailPlus Server licences expire?
No. MailPlus Server licences are perpetual they do not expire and do not require annual renewal. Once purchased, they remain valid indefinitely for the version they were licensed for. There are no subscription fees, no renewal reminders and no price increases on existing licences.
What is the minimum number of licences to purchase?
The minimum purchase is a 5-user licence pack. Since 5 licences are included free with qualifying NAS models, the first additional purchase takes you from 5 to 10 users. You cannot purchase a single-user licence or a 2-user pack the smallest purchasable increment is 5 users.
Can I use MailPlus Server licences on multiple NAS devices?
Licences are associated with a Synology account and activated on a specific NAS at a time. You can have multiple NAS devices with MailPlus Server, but each device requires its own licences. Licences are not pooled across devices a 20-user licence on Device A cannot cover users on Device B.
Do MailPlus Server licences cover MailPlus (the webmail client) too?
Yes. MailPlus (the webmail client) has no separate licence. Installing MailPlus Server and purchasing user licences covers both the server and the webmail client. There is no additional cost for the MailPlus web interface or the MailPlus mobile apps. See our MailPlus vs MailPlus Server guide for the distinction between the two packages.
Can I downgrade my licence count to save money?
Licences cannot be refunded or returned once purchased. If an organisation shrinks and has excess licences, the spare slots remain allocated but unused there is no mechanism to sell back licences to Synology. The practical approach for a downsizing organisation is to stop purchasing additional licences and allow natural attrition to bring the active account count in line with available licences over time.
Conclusion
MailPlus Server’s perpetual licence model works differently from cloud email economics. The cost comparison favours MailPlus Server significantly over a three-to-five-year horizon for organisations already running Synology NAS infrastructure but the administration requirement and hardware dependency are real costs that the licence price does not capture.
The two most common planning mistakes: underestimating how many licences are needed by forgetting shared mailboxes that are standalone accounts rather than aliases and assuming that deactivating departed employees frees their licence slots when it does not.
How many active mailboxes does your organisation run and of those, how many are standalone shared mailboxes rather than personal accounts? That count is the accurate input for licence planning, not just the headcount.