Which Synology NAS Models Support MailPlus, and How Many Users?
Updated on September 10, 2026
5 min read
Not every Synology NAS can run a mail server. MailPlus models are Plus-series and above — the J and Value lines cannot install MailPlus Server at all — and among the models that can, the one you pick decides how many mailboxes and how much daily mail the server will comfortably carry. This page lists the supported MailPlus models by series, then the per-model user and throughput ratings.
Which Synology NAS Models Support MailPlus? #
The supported MailPlus models below are grouped by hardware series. If your unit is not on the list, the package will not appear in Package Center — that is the quickest way to check without reading a list at all.
- FS series: FS6400, FS3600, FS3410, FS3400, FS3017, FS2500, FS2017, FS1018
- HD series: HD6500
- SA series: SA6400, SA3610, SA3600, SA3410, SA3400D, SA3400, SA3200D
- 24 series: DS224+
- 23 series: RS2423RP+, RS2423+, DS1823xs+, DS923+, DS723+, DS423+
- 22 series: RS822RP+, RS822+, DS3622xs+, DS2422+, DS1522+, DVA1622
- 21 series: RS4021xs+, RS3621xs+, RS3621RPxs, RS2821RP+, RS2421RP+, RS2421+, RS1221RP+, RS1221+, DS1821+, DS1621xs+, DS1621+, DVA3221
- 20 series: RS820RP+, RS820+, DS1520+, DS920+, DS720+, DS620slim, DS420+, DS220+
- 19 series: RS1619xs+, RS1219+, DS2419+II, DS2419+, DS1819+, DS1019+, DVA3219
- 18 series: RS3618xs, RS2818RP+, RS2418RP+, RS2418+, RS818RP+, RS818+, DS3018xs, DS1618+, DS918+, DS718+, DS418play, DS218+
- 17 series: RS18017xs+, RS4017xs+, RS3617xs+, RS3617RPxs, RS3617xs, DS3617xsII, DS3617xs, DS1817+, DS1517+
- 16 series: RS18016xs+, RS2416RP+, RS2416+, DS916+, DS716+II, DS716+, DS416play, DS216+II, DS216+
Synology adds MailPlus models as new hardware ships, so treat the list above as a snapshot rather than the final word. The live version is maintained by Synology here: MailPlus Server — applied models. Newer MailPlus models that are not yet listed above are usually supported; ask us if you want it confirmed before you buy.
How Many Email Accounts the MailPlus Models Handle #
And their recommended supported registered and concurrent users numbers are:
| Model | Maximum number of users | Maximum number of concurrent users | Maximum server performance |
|---|---|---|---|
| FS6400 | 17500 | 3500 | 5,721,000 emails per day, approx. 174GB |
| FS3600 | 12000 | 2400 | 5,040,000 emails per day, approx. 151 GB |
| FS3410 | 10000 | 2000 | 4,471,000 emails per day, approx. 136 GB |
| FS2500 | 2250 | 450 | 3,486,240 emails per day, approx. 102 GB |
| HD6500 | 20000 | 4000 | 3,523,133 emails per day, approx. 103.7 GB |
| SA6400 | 14000 | 2800 | 5,721,000 emails per day, approx. 174 GB |
| SA3610 | 12000 | 2400 | 5,040,000 emails per day, approx. 151 GB |
| SA3410 | 10000 | 2000 | 4,312,000 emails per day, approx. 131 GB |
| SA3400D | 10000 | 2000 | 4,312,000 emails per day, approx. 131 GB |
| SA3200D | 2500 | 500 | 3,595,000 emails per day, approx. 109 GB |
| RS4021xs+ | 10000 | 2000 | 4,312,000 emails per day, approx. 131GB |
| RS3621xs+ | 10000 | 2000 | 4,235,000 emails per day, approx. 129GB |
| RS3621RPxs | 4000 | 800 | 4,235,000 emails per day, approx. 129GB |
| RS3618xs | 2500 | 500 | 3,595,000 emails per day, approx. 109GB |
| RS2821RP+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS2423RP+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS2423+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS1619xs+ | 2250 | 450 | 3,363,000 emails per day, approx. 102.6 GB |
| RS1221RP+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS1221+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS822RP+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| RS822+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| DS3622xs+ | 7500 | 1500 | 4,235,000 emails per day, approx. 129 GB |
| DS2422+ | 750 | 150 | 1,484,000 emails per day, approx. 45 GB |
| DS1823xs+ | 2250 | 450 | 2,029,000 emails per day, approx. 59GB |
| DS1821+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| DS1621+ | 750 | 150 | 1,484,000 emails per day, approx. 45GB |
| DS1522+ | 500 | 100 | 1,224,000 emails per day, approx. 37GB |
| DS923+ | 500 | 100 | 1,224,000 emails per day, approx. 37GB |
| DS723+ | 500 | 100 | 1,224,000 emails per day, approx. 37GB |
| DS620slim | 250 | 50 | 181,000 emails per day, approx. 5.5GB |
| DS423+ | 500 | 100 | 1,224,000 emails per day, approx. 37GB |
| DS224+ | 500 | 100 | 1,224,000 emails per day, approx. 37GB |
Reading Those Numbers: Registered vs Concurrent vs Throughput #
The three columns on that table answer different questions, and mixing them up is how people over-buy or under-buy hardware. All three vary by model, so read them together rather than picking the biggest number.
- Maximum number of users is how many mailboxes may exist on the server. This is the number to compare against your headcount.
- Maximum concurrent users is how many are actively connected at once. In practice this lands around a fifth of the registered figure, which is a realistic office pattern rather than a hard cliff.
- Maximum server performance is the daily mail volume and the storage it implies. It matters for mailing-heavy operations and for sizing the volume, not for counting seats.
For most small businesses the registered-user ceiling is nowhere near the constraint. A DS923+ is rated for 500 users; a forty-person company will run out of disk long before it runs out of that. Among the smaller MailPlus models the exception is the DS620slim, rated for 250 users but only about 181,000 emails a day — a fraction of what its siblings handle.
Count Your Free Accounts Before Counting Licences #
Hardware support and licence count are separate questions. Every MailPlus Server installation includes five free email accounts regardless of which of the MailPlus models you run it on, a free Virtual DSM guest adds another five of its own, and a high-availability pair starts at ten. Aliases never consume a licence.
Only once you pass those free accounts do you need a licence pack. How the packs work and how to enter a key, with screenshots: Receive and Install Synology MailPlus License Guide.
Choosing Between MailPlus Models #
If you are still deciding whether to self-host at all, the wider picture — cost against Google Workspace and Microsoft 365, the DNS work that decides deliverability, and migrating existing mailboxes — is covered here: Synology MailPlus: the complete guide to running your own mail server.
And if you would rather not work through the table yourself, tell us your headcount and expected mail volume and we will tell you which of the MailPlus models fits, including whether you are better off with a smaller unit plus a high-availability partner than a single larger one.
Have question? Just ask SynoPower Club.