diff --git a/src/app/components/EmailNotificationsInfo.svelte b/src/app/components/EmailNotificationsInfo.svelte
new file mode 100644
index 00000000..27b2f04e
--- /dev/null
+++ b/src/app/components/EmailNotificationsInfo.svelte
@@ -0,0 +1,26 @@
+<script lang="ts">
+  import Button from "@lib/components/Button.svelte"
+  import Modal from "@lib/components/Modal.svelte"
+  import ModalBody from "@lib/components/ModalBody.svelte"
+  import ModalHeader from "@lib/components/ModalHeader.svelte"
+  import ModalTitle from "@lib/components/ModalTitle.svelte"
+  import {popModal} from "@app/modal"
+
+  const gotIt = () => popModal()
+</script>
+
+<Modal
+  ><ModalBody>
+    <ModalHeader>
+      <ModalTitle>Email notifications</ModalTitle>
+    </ModalHeader>
+    <p>
+      For a community's new messages to appear in your email digest, its relay must support NIP-9a
+      (email notifications).
+    </p>
+    <p>
+      If a community is missing from your digest, ask the community admin to enable NIP-9a on their
+      relay.
+    </p>
+    <Button class="button button-primary" onclick={gotIt}>Got it</Button>
+  </ModalBody></Modal>
diff --git a/src/routes/settings/alerts/+page.svelte b/src/routes/settings/alerts/+page.svelte
index 34f23921..58776c57 100644
--- a/src/routes/settings/alerts/+page.svelte
+++ b/src/routes/settings/alerts/+page.svelte
@@ -1,6 +1,8 @@
 <script lang="ts">
   import cx from "classnames"
+  import {derived} from "svelte/store"
   import {sleep} from "@welshman/lib"
+  import type {Relay} from "@welshman/domain"
   import {Capacitor} from "@capacitor/core"
   import {Badge} from "@capawesome/capacitor-badge"
   import Bell from "@assets/icons/bell.svg?dataurl"
@@ -12,12 +14,16 @@
   import Button from "@lib/components/Button.svelte"
   import PageContent from "@lib/components/PageContent.svelte"
   import {pushToast} from "@app/toast"
+  import {pushModal} from "@app/modal"
   import {clearBadges} from "@app/notifications"
   import {Push} from "@app/push"
   import {Mail} from "@app/mail"
   import {notificationSettings, publishSettings, userSettingsValues} from "@app/settings"
   import {emailNotificationState} from "@app/push/adapters/common"
   import {EMAIL_NOTIFICATION_SERVER} from "@app/env"
+  import {relays} from "@app/core"
+  import {userSpaceUrls} from "@app/rooms"
+  import EmailNotificationsInfo from "@app/components/EmailNotificationsInfo.svelte"
 
   const clearError = () => {
     if ($emailNotificationState.error) {
@@ -112,6 +118,34 @@
     }
   })
 
+  // Communities whose relay doesn't advertise NIP-9a won't be included in the email digest.
+  // Subscribing to each space's NIP-11 info triggers a fetch for any that hasn't loaded yet.
+  const communitiesWithoutEmail = derived(
+    userSpaceUrls,
+    ($urls, set: (value: string[]) => void) => {
+      const unsubscribers = $urls.map(url =>
+        relays
+          .get()
+          .one(url)
+          .subscribe(() =>
+            set(
+              $urls
+                .map(url => relays.get().get(url))
+                .filter((relay): relay is Relay => relay !== undefined && !relay.hasNip("9a"))
+                .map(relay => relay.display()),
+            ),
+          ),
+      )
+
+      return () =>
+        unsubscribers.forEach(unsubscribe => {
+          unsubscribe()
+        })
+    },
+  )
+
+  const showEmailInfo = () => pushModal(EmailNotificationsInfo)
+
   let loading = $state(false)
   let settings = $state(buildSettings())
 </script>
@@ -198,6 +232,23 @@
           {/snippet}
         </FieldInline>
         {#if settings.email}
+          {#if $communitiesWithoutEmail.length > 0}
+            <div class="flex flex-col gap-1 rounded-2xl border border-warning bg-warning/10 p-4">
+              <p class="flex items-center gap-2 text-sm text-warning">
+                {#if $communitiesWithoutEmail.length === 1}
+                  1 of your communities does not support email notifications.
+                {:else}
+                  {$communitiesWithoutEmail.length} of your communities do not support email notifications.
+                {/if}
+                <Button class="link" onclick={showEmailInfo}>Learn more</Button>
+              </p>
+              <ul class="list-inside list-disc text-sm text-warning">
+                {#each $communitiesWithoutEmail as name (name)}
+                  <li>{name}</li>
+                {/each}
+              </ul>
+            </div>
+          {/if}
           <FieldInline>
             {#snippet label()}
               <p>Email address</p>