[WebUI] "Invalid key for object" error on Match Condition when creating a new Outbound Rate Limiter

[Chris_Nguyen]

Issue Description

When attempting to create a new Outbound Rate Limiter via the Stalwart WebUI administration portal, the system prevents form submission and displays an “Invalid key for object” validation error under the “Match condition” section.

According to the official Stalwart documentation for Outbound Limits[Rate Limits | Stalwart], the Match condition field is optional and should be allowed to remain empty if no specific imposition rules are required. However, the WebUI enforces an invalid validation block even when no conditions have been added.

Actual Behavior

An error message “Invalid key for object” is displayed in red at the bottom of the empty Match condition block, blocking the form submission and preventing the throttle from being created.

Reproduction Steps

1, Navigate to Settings > MTA > Outbound > Outbound Rate Limits.
2, Click on Create throttle (or go directly to the new outbound throttle URL).
3, Fill in the required fields:

• Description: e.g., all emails
• Rate limit: e.g., 300 per 1 Hours

Leave the Keys checkboxes unselected and do NOT click “+ Add condition” under Match condition (leave it entirely blank).

Look at the bottom of the “Match condition” section.

Stalwart Version

v0.16.x

Installation Method

Binary (Linux)

Database Backend

RocksDB

Blob Storage

RocksDB

Search Engine

Internal

Directory Backend

Internal

I have reviewed the documentation and FAQ and confirm that my issue is NOT addressed there.

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I have searched this support forum (open and closed topics) and confirm this is not a duplicate.

on

I understand that topics in this category are triaged by a bot first but a human reply will follow up. If I’d prefer a human-only reply, I’ll add the no-ai tag to my topic.

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[helpbot]

Let me look into this WebUI validation issue for the outbound rate limiter.

This is a confirmed WebUI bug. The match field on MtaOutboundThrottle is documented as optional, with a default of {"else":"true"} when left blank. The WebUI should not be emitting an “Invalid key for object” validation error and blocking submission when the Match condition is left empty.

Workaround: You can bypass the WebUI entirely and create the throttle directly via the JMAP API. Here is an example that omits the match field entirely (the server will apply the default {"else":"true"}):

curl -X POST https://mail.example.com/api \
  -H 'Authorization: Bearer $TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{
      "methodCalls": [
        [
          "x:MtaOutboundThrottle/set",
          {
            "create": {
              "new1": {
                "description": "all emails",
                "rate": {"count": 300, "period": "1h"}
              }
            }
          },
          "c1"
        ]
      ],
      "using": [
        "urn:ietf:params:jmap:core",
        "urn:stalwart:jmap"
      ]
    }'

Replace https://mail.example.com/api with your server URL and $TOKEN with a valid admin bearer token. You can omit key and match entirely when no scoping or condition is needed.

The underlying bug – the WebUI enforcing validation on an optional field – will need to be addressed by the maintainers. A human will follow up on this thread.

Reference: MtaOutboundThrottle object reference

This is an automated reply from the Stalwart Help Bot. Other community members may follow up if this answer is incomplete or wrong.

[Chris_Nguyen]

More evidences:

Documentation: