diff --git a/docs/UI_UX_DECISION_LEDGER.md b/docs/UI_UX_DECISION_LEDGER.md
index 02a56b8..60f67bc 100644
--- a/docs/UI_UX_DECISION_LEDGER.md
+++ b/docs/UI_UX_DECISION_LEDGER.md
@@ -223,6 +223,10 @@ instead of reproducing their behavior.
 - `help` content is contextual guidance, not the accessible name. The persisted
   `show_inline_help_hints` user preference hides only the `InlineHelp` marker by
   applying `ui-hide-help-hints` at the document root.
+- Shared action-bearing components accept an optional disabled reason. In
+  particular, `MailServerSettingsPanel` forwards protocol-specific test
+  blockers into the shared focusable disabled-action tooltip; modules provide
+  the domain-specific required field, permission, or in-progress reason.
 - A dirty editor registers once with `useUnsavedDraftGuard`. An explicit
   Discard button calls `useUnsavedChanges().requestDiscard(afterResolve)`; SPA
   navigation uses `useGuardedNavigate` or `requestNavigation`. Both paths show
diff --git a/webui/src/components/mail/MailServerSettingsPanel.tsx b/webui/src/components/mail/MailServerSettingsPanel.tsx
index 593e244..53f5601 100644
--- a/webui/src/components/mail/MailServerSettingsPanel.tsx
+++ b/webui/src/components/mail/MailServerSettingsPanel.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useRef, useState } from "react";
+import { useEffect, useRef, useState, type ReactNode } from "react";
 import Button from "../Button";
 import { CredentialFields } from "../CredentialPanel";
 import DismissibleAlert from "../DismissibleAlert";
@@ -64,11 +64,13 @@ export type MailServerSettingsPanelProps = {
   smtpPasswordSaved?: boolean;
   smtpSavedPasswordPlaceholder?: string;
   smtpActionDisabled?: boolean;
+  smtpActionDisabledReason?: ReactNode;
   imapServerDisabled?: boolean;
   imapCredentialDisabled?: boolean;
   imapPasswordSaved?: boolean;
   imapSavedPasswordPlaceholder?: string;
   imapActionDisabled?: boolean;
+  imapActionDisabledReason?: ReactNode;
   smtpTestLabel?: string;
   imapTestLabel?: string;
   busyAction?: "smtp" | "imap" | "folders" | string | null;
@@ -209,11 +211,13 @@ export default function MailServerSettingsPanel({
   smtpPasswordSaved = false,
   smtpSavedPasswordPlaceholder = "••••••••",
   smtpActionDisabled = smtpDisabled,
+  smtpActionDisabledReason,
   imapServerDisabled = false,
   imapCredentialDisabled = imapServerDisabled,
   imapPasswordSaved = false,
   imapSavedPasswordPlaceholder = "••••••••",
   imapActionDisabled = imapServerDisabled,
+  imapActionDisabledReason,
   smtpTestLabel = "i18n:govoplan-core.test_smtp.e5697981",
   imapTestLabel = "i18n:govoplan-core.test_imap.ef1bd79c",
   busyAction = null,
@@ -323,7 +327,7 @@ export default function MailServerSettingsPanel({
             </div>
             {onTestSmtp &&
           <div className="button-row compact-actions mail-server-actions">
-                <Button type="button" variant="primary" onClick={onTestSmtp} disabled={smtpActionsDisabled || busyAction === "smtp"}>{busyAction === "smtp" ? "i18n:govoplan-core.testing.15ccc832" : smtpTestLabel}</Button>
+                <Button type="button" variant="primary" onClick={onTestSmtp} disabled={smtpActionsDisabled || busyAction === "smtp"} disabledReason={busyAction === "smtp" ? "SMTP connection testing is already running." : smtpActionsDisabled ? smtpActionDisabledReason : undefined}>{busyAction === "smtp" ? "i18n:govoplan-core.testing.15ccc832" : smtpTestLabel}</Button>
               </div>
           }
             <MailServerActionResult result={smtpTestResult} floating={floatingResults} />
@@ -352,7 +356,7 @@ export default function MailServerSettingsPanel({
             </div>
             {onTestImap &&
           <div className="button-row compact-actions mail-server-actions">
-                <Button type="button" variant="primary" onClick={onTestImap} disabled={imapActionsDisabled || busyAction === "imap"}>{busyAction === "imap" ? "i18n:govoplan-core.testing.15ccc832" : imapTestLabel}</Button>
+                <Button type="button" variant="primary" onClick={onTestImap} disabled={imapActionsDisabled || busyAction === "imap"} disabledReason={busyAction === "imap" ? "IMAP connection testing is already running." : imapActionsDisabled ? imapActionDisabledReason : undefined}>{busyAction === "imap" ? "i18n:govoplan-core.testing.15ccc832" : imapTestLabel}</Button>
               </div>
           }
             <MailServerActionResult result={imapTestResult} floating={floatingResults} />
diff --git a/webui/tests/mail-components.test.tsx b/webui/tests/mail-components.test.tsx
index cfe2690..59181da 100644
--- a/webui/tests/mail-components.test.tsx
+++ b/webui/tests/mail-components.test.tsx
@@ -108,6 +108,20 @@ assert(!settingsPanel.includes("i18n:govoplan-core.advanced.4d064726"), "advance
 assert(!settingsPanel.includes("Enable IMAP"), "legacy IMAP enable toggle is not rendered");
 assert(settingsPanel.includes('placeholder="Saved SMTP password"'), "SMTP saved credential placeholder is rendered");
 
+const disabledSettingsPanel = renderToStaticMarkup(
+  <MailServerSettingsPanel
+    smtp={{ host: "", port: 587, security: "starttls", timeout_seconds: 30 }}
+    imap={{ host: "", port: 993, security: "tls", sent_folder: "auto", timeout_seconds: 30 }}
+    onSmtpChange={noop}
+    onImapChange={noop}
+    onTestSmtp={noop}
+    smtpActionDisabled
+    smtpActionDisabledReason="Enter an SMTP server hostname before testing the connection."
+  />
+);
+assert(disabledSettingsPanel.includes("disabled-action-tooltip"), "disabled SMTP test reason uses the shared focusable tooltip");
+assert(disabledSettingsPanel.includes('tabindex="0"'), "disabled SMTP test reason is keyboard focusable");
+
 const imapSettingsPanel = renderToStaticMarkup(
   <MailServerSettingsPanel
     initialSection="imap"