diff --git a/js/src/i18n/en_US.json b/js/src/i18n/en_US.json
index 8c2f768f0..e34bb1e44 100644
--- a/js/src/i18n/en_US.json
+++ b/js/src/i18n/en_US.json
@@ -1251,5 +1251,6 @@
   "Approve member": "Approve member",
   "Reject member": "Reject member",
   "The membership request from {profile} was rejected": "The membership request from {profile} was rejected",
-  "The member was approved": "The member was approved"
+  "The member was approved": "The member was approved",
+  "Emails usually don't contain capitals, make sure you haven't made a typo.": "Emails usually don't contain capitals, make sure you haven't made a typo."
 }
diff --git a/js/src/i18n/fr_FR.json b/js/src/i18n/fr_FR.json
index 3d475c107..72ec50fa8 100644
--- a/js/src/i18n/fr_FR.json
+++ b/js/src/i18n/fr_FR.json
@@ -1355,5 +1355,6 @@
   "Approve member": "Approuver le ou la membre",
   "Reject member": "Rejeter le ou la membre",
   "The membership request from {profile} was rejected": "La demande d'adhésion de {profile} a été rejetée",
-  "The member was approved": "Le ou la membre a été approuvée"
+  "The member was approved": "Le ou la membre a été approuvée",
+  "Emails usually don't contain capitals, make sure you haven't made a typo.": "Les emails ne contiennent d'ordinaire pas de capitales, assurez-vous de n'avoir pas fait de faute de frappe."
 }
diff --git a/js/src/types/apollo.ts b/js/src/types/apollo.ts
new file mode 100644
index 000000000..244b56005
--- /dev/null
+++ b/js/src/types/apollo.ts
@@ -0,0 +1,5 @@
+import { GraphQLError } from "graphql/error/GraphQLError";
+
+export class AbsintheGraphQLError extends GraphQLError {
+  readonly field: string | undefined;
+}
diff --git a/js/src/views/User/Register.vue b/js/src/views/User/Register.vue
index a1638a75d..bb7710963 100644
--- a/js/src/views/User/Register.vue
+++ b/js/src/views/User/Register.vue
@@ -83,8 +83,8 @@
           <form v-on:submit.prevent="submit()">
             <b-field
               :label="$t('Email')"
-              :type="errors.email ? 'is-danger' : null"
-              :message="errors.email"
+              :type="errorEmailType"
+              :message="errorEmailMessages"
               label-for="email"
             >
               <b-input
@@ -100,8 +100,8 @@
 
             <b-field
               :label="$t('Password')"
-              :type="errors.password ? 'is-danger' : null"
-              :message="errors.password"
+              :type="errorPasswordType"
+              :message="errorPasswordMessages"
               label-for="password"
             >
               <b-input
@@ -178,12 +178,6 @@
               <auth-providers :oauthProviders="config.auth.oauthProviders" />
             </div>
           </form>
-
-          <div v-if="errors.length > 0">
-            <b-message type="is-danger" v-for="error in errors" :key="error">{{
-              error
-            }}</b-message>
-          </div>
         </div>
       </div>
     </section>
@@ -191,13 +185,18 @@
 </template>
 
 <script lang="ts">
-import { Component, Prop, Vue } from "vue-property-decorator";
+import { Component, Prop, Vue, Watch } from "vue-property-decorator";
 import { CREATE_USER } from "../../graphql/user";
 import RouteName from "../../router/name";
 import { IConfig } from "../../types/config.model";
 import { CONFIG } from "../../graphql/config";
 import Subtitle from "../../components/Utils/Subtitle.vue";
 import AuthProviders from "../../components/User/AuthProviders.vue";
+import { AbsintheGraphQLError } from "../../types/apollo";
+
+type errorType = "is-danger" | "is-warning";
+type errorMessage = { type: errorType; message: string };
+type credentials = { email: string; password: string; locale: string };
 
 @Component({
   components: { Subtitle, AuthProviders },
@@ -218,13 +217,14 @@ export default class Register extends Vue {
 
   @Prop({ type: String, required: false, default: "" }) password!: string;
 
-  credentials = {
+  credentials: credentials = {
     email: this.email,
     password: this.password,
     locale: "en",
   };
 
-  errors: string[] = [];
+  emailErrors: errorMessage[] = [];
+  passwordErrors: errorMessage[] = [];
 
   sendingForm = false;
 
@@ -245,7 +245,8 @@ export default class Register extends Vue {
     this.sendingForm = true;
     this.credentials.locale = this.$i18n.locale;
     try {
-      this.errors = [];
+      this.emailErrors = [];
+      this.passwordErrors = [];
 
       await this.$apollo.mutate({
         mutation: CREATE_USER,
@@ -257,17 +258,67 @@ export default class Register extends Vue {
         params: { email: this.credentials.email },
       });
     } catch (error: any) {
-      console.error(error);
-      this.errors = error.graphQLErrors.reduce(
-        (acc: string[], localError: any) => {
-          acc.push(localError.message);
-          return acc;
-        },
-        []
+      error.graphQLErrors.forEach(
+        ({ field, message }: AbsintheGraphQLError) => {
+          switch (field) {
+            case "email":
+              this.emailErrors.push({
+                type: "is-danger" as errorType,
+                message: message[0] as string,
+              });
+              break;
+            case "password":
+              this.passwordErrors.push({
+                type: "is-danger" as errorType,
+                message: message[0] as string,
+              });
+              break;
+            default:
+          }
+        }
       );
+
       this.sendingForm = false;
     }
   }
+
+  @Watch("credentials", { deep: true })
+  watchCredentials(credentials: credentials): void {
+    if (credentials.email !== credentials.email.toLowerCase()) {
+      const error = {
+        type: "is-warning" as errorType,
+        message: this.$t(
+          "Emails usually don't contain capitals, make sure you haven't made a typo."
+        ) as string,
+      };
+      this.emailErrors = [error];
+      this.$forceUpdate();
+    }
+  }
+
+  maxErrorType(errors: errorMessage[]): errorType | undefined {
+    if (!errors || errors.length === 0) return undefined;
+    return errors.reduce<errorType>((acc, error) => {
+      if (error.type === "is-danger" || acc === "is-danger") return "is-danger";
+      return "is-warning";
+    }, "is-warning");
+  }
+
+  get errorEmailType(): errorType | undefined {
+    return this.maxErrorType(this.emailErrors);
+  }
+
+  get errorPasswordType(): errorType | undefined {
+    return this.maxErrorType(this.passwordErrors);
+  }
+
+  get errorEmailMessages(): string[] {
+    return this.emailErrors.map(({ message }) => message);
+  }
+
+  get errorPasswordMessages(): string[] {
+    return this.passwordErrors?.map(({ message }) => message);
+  }
 }
 </script>
 
@@ -302,4 +353,7 @@ p.create-account {
     margin: 1rem auto 2rem;
   }
 }
+::v-deep .help.is-warning {
+  color: #755033;
+}
 </style>
diff --git a/lib/graphql/resolvers/user.ex b/lib/graphql/resolvers/user.ex
index 430bc6b48..afbd0909f 100644
--- a/lib/graphql/resolvers/user.ex
+++ b/lib/graphql/resolvers/user.ex
@@ -145,13 +145,17 @@ defmodule Mobilizon.GraphQL.Resolvers.User do
   """
   @spec create_user(any, %{email: String.t()}, any) :: {:ok, User.t()} | {:error, String.t()}
   def create_user(_parent, %{email: email} = args, _resolution) do
-    with :registration_ok <- check_registration_config(email),
+    with {:ok, email} <- lowercase_domain(email),
+         :registration_ok <- check_registration_config(email),
          :not_deny_listed <- check_registration_denylist(email),
-         {:ok, %User{} = user} <- Users.register(args),
+         {:ok, %User{} = user} <- Users.register(%{args | email: email}),
          %Bamboo.Email{} <-
            Email.User.send_confirmation_email(user, Map.get(args, :locale, "en")) do
       {:ok, user}
     else
+      {:error, :invalid_email} ->
+        {:error, dgettext("errors", "Your email seems to be using an invalid format")}
+
       :registration_closed ->
         {:error, dgettext("errors", "Registrations are not open")}
 
@@ -190,24 +194,40 @@ defmodule Mobilizon.GraphQL.Resolvers.User do
     # Remove everything behind the +
     email = String.replace(email, ~r/(\+.*)(?=\@)/, "")
 
-    if email_in_list(email, Config.instance_registrations_denylist()),
+    if email_in_list?(email, Config.instance_registrations_denylist()),
       do: :deny_listed,
       else: :not_deny_listed
   end
 
   @spec check_allow_listed_email(String.t()) :: :registration_ok | :not_allowlisted
   defp check_allow_listed_email(email) do
-    if email_in_list(email, Config.instance_registrations_allowlist()),
+    if email_in_list?(email, Config.instance_registrations_allowlist()),
       do: :registration_ok,
       else: :not_allowlisted
   end
 
-  defp email_in_list(email, list) do
-    [_, domain] = String.split(email, "@", parts: 2, trim: true)
+  @spec email_in_list?(String.t(), list(String.t())) :: boolean()
+  defp email_in_list?(email, list) do
+    [_, domain] = split_email(email)
 
     domain in list or email in list
   end
 
+  # Domains should always be lower-case, so let's force that
+  @spec lowercase_domain(String.t()) :: {:ok, String.t()} | {:error, :invalid_email}
+  defp lowercase_domain(email) do
+    case split_email(email) do
+      [user_part, domain_part] ->
+        {:ok, "#{user_part}@#{String.downcase(domain_part)}"}
+
+      _ ->
+        {:error, :invalid_email}
+    end
+  end
+
+  @spec split_email(String.t()) :: list(String.t())
+  defp split_email(email), do: String.split(email, "@", parts: 2, trim: true)
+
   @doc """
   Validate an user, get its actor and a token
   """
diff --git a/test/graphql/resolvers/user_test.exs b/test/graphql/resolvers/user_test.exs
index 293fcb212..0f77eae21 100644
--- a/test/graphql/resolvers/user_test.exs
+++ b/test/graphql/resolvers/user_test.exs
@@ -454,6 +454,21 @@ defmodule Mobilizon.GraphQL.Resolvers.UserTest do
       Config.put([:instance, :registration_email_denylist], [])
     end
 
+    test "create_user/3 lowers domain part of email",
+         %{
+           conn: conn
+         } do
+      res =
+        conn
+        |> AbsintheHelpers.graphql_query(
+          query: @create_user_mutation,
+          variables: Map.put(@user_creation, :email, "test+alias@DEMO.tld")
+        )
+
+      assert res["errors"] == nil
+      assert res["data"]["createUser"]["email"] == "test+alias@demo.tld"
+    end
+
     test "register_person/3 doesn't register a profile from an unknown email", %{conn: conn} do
       conn
       |> put_req_header("accept-language", "fr")