Foundry376/Mailspring · error

Unknown mail rule condition template: ${condition.templateKe

Error message

Unknown mail rule condition template: ${condition.templateKey}

What it means

Warning (not a throw) logged by _checkRuleForMessage when a stored rule condition references a templateKey absent from the ConditionTemplates registry — e.g. a rule created by a different app version or removed condition type. The condition cannot be evaluated, so it cannot contribute to the rule matching.

Source

Thrown at app/src/mail-rules-processor.ts:226

      for (const t of ConditionTemplates) {
        this._conditionTemplateMap.set(t.key, t);
      }
    }
    return this._conditionTemplateMap;
  }

  _checkRuleForMessage(rule: MailRule, message: Message) {
    const fn =
      rule.conditionMode === ConditionMode.All ? Array.prototype.every : Array.prototype.some;
    if (message.accountId !== rule.accountId) {
      return false;
    }

    const templateMap = this._getConditionTemplateMap();
    return fn.call(rule.conditions, (condition) => {
      const template = templateMap.get(condition.templateKey);
      if (!template) {
        console.warn(`Unknown mail rule condition template: ${condition.templateKey}`);
        return false;
      }
      const value = template.valueForMessage(message);
      return template.evaluate(condition, value);
    });
  }

  async _applyRuleToMessage(rule: MailRule, message: Message, thread: Thread) {
    try {
      const actionPromises = rule.actions.map((action) => {
        const actionFn = MailRulesActions[action.templateKey];
        if (!actionFn) {
          throw new Error(`${action.templateKey} is not a supported action.`);
        }
        return actionFn(message, thread, action.value);
      });

      const actionResults = await Promise.all<Task | undefined>(actionPromises);

View on GitHub (pinned to 648c685d60)

Solutions

1. Edit the rule in Preferences > Mail Rules and re-select the condition
2. Update Mailspring to a version that includes the condition template
3. Delete and recreate the affected rule

When it happens

Trigger: Thrown at app/src/mail-rules-processor.ts:226 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Foundry376/Mailspring@648c685d60 (2026-09-03). Data as JSON: /api/errors/84f017894c2abcd6. Report an issue: GitHub.