diff --git a/apps/participation/forms.py b/apps/participation/forms.py
index de77aba..44663ea 100644
--- a/apps/participation/forms.py
+++ b/apps/participation/forms.py
@@ -17,11 +17,22 @@ class TeamForm(forms.ModelForm):
     """
     Form to create a team, with the name and the trigram,...
     """
+    def clean_name(self):
+        if "name" in self.cleaned_data:
+            name = self.cleaned_data["name"].upper()
+            if not self.instance.pk and Team.objects.filter(name=name).exists():
+                raise ValidationError(_("This name is already used."))
+            return name
+
     def clean_trigram(self):
-        trigram = self.cleaned_data["trigram"].upper()
-        if not re.match("[A-Z]{3}", trigram):
-            raise ValidationError(_("The trigram must be composed of three uppercase letters."))
-        return trigram
+        if "trigram" in self.cleaned_data:
+            trigram = self.cleaned_data["trigram"].upper()
+            if not re.match("[A-Z]{3}", trigram):
+                raise ValidationError(_("The trigram must be composed of three uppercase letters."))
+
+            if not self.instance.pk and Team.objects.filter(trigram=trigram).exists():
+                raise ValidationError(_("This trigram is already used."))
+            return trigram
 
     class Meta:
         model = Team
diff --git a/apps/participation/management/commands/fix_sympa_lists.py b/apps/participation/management/commands/fix_sympa_lists.py
index 404309a..73abb90 100644
--- a/apps/participation/management/commands/fix_sympa_lists.py
+++ b/apps/participation/management/commands/fix_sympa_lists.py
@@ -56,10 +56,11 @@ class Command(BaseCommand):
 
         for team in Team.objects.filter(Q(participation__valid=False) | Q(participation__valid__isnull=True)).all():
             team.create_mailing_list()
-            sympa.subscribe(team.email, "equipes-non-valides", f"Equipe {team.name}", True)
+            sympa.subscribe(team.email, "equipes-non-valides", True, f"Equipe {team.name}")
 
         for participant in ParticipantRegistration.objects.filter(team__isnull=False).all():
-            sympa.subscribe(participant.user.email, f"equipe-{participant.team.trigram.lower}", True, f"{participant}")
+            sympa.subscribe(participant.user.email, f"equipe-{participant.team.trigram.lower()}",
+                            True, f"{participant}")
 
         for volunteer in VolunteerRegistration.objects.all():
             for organized_tournament in volunteer.organized_tournaments.all():
diff --git a/apps/participation/views.py b/apps/participation/views.py
index 2672467..7362839 100644
--- a/apps/participation/views.py
+++ b/apps/participation/views.py
@@ -225,7 +225,7 @@ class TeamDetailView(LoginRequiredMixin, FormMixin, ProcessFormView, DetailView)
         mail_context = dict(team=self.object, domain=Site.objects.first().domain)
         mail_plain = render_to_string("participation/mails/request_validation.txt", mail_context)
         mail_html = render_to_string("participation/mails/request_validation.html", mail_context)
-        send_mail("[TFJM²] Validation d'équipe", mail_plain, [settings.DEFAULT_FROM_EMAIL],
+        send_mail("[TFJM²] Validation d'équipe", mail_plain, settings.DEFAULT_FROM_EMAIL,
                   [self.object.participation.tournament.organizers_email], html_message=mail_html)
 
         return super().form_valid(form)
@@ -234,8 +234,9 @@ class TeamDetailView(LoginRequiredMixin, FormMixin, ProcessFormView, DetailView)
         """
         An admin validates the team (or not)
         """
-        if not self.object.participation.tournament \
-                or self.request.user.registration not in self.object.participation.tournament.organizers.all():
+        if not self.request.user.registration.is_admin and \
+                (not self.object.participation.tournament
+                 or self.request.user.registration not in self.object.participation.tournament.organizers.all()):
             form.add_error(None, _("You are not an organizer of the tournament."))
             return self.form_invalid(form)
         elif self.object.participation.valid is not False:
diff --git a/apps/registration/templates/registration/user_list.html b/apps/registration/templates/registration/user_list.html
index 78f3cbe..179a41b 100644
--- a/apps/registration/templates/registration/user_list.html
+++ b/apps/registration/templates/registration/user_list.html
@@ -3,7 +3,7 @@
 {% load django_tables2 i18n %}
 
 {% block content %}
-    {% if user.registration.is_admin %}
+    {% if user.registration.is_volunteer %}
         <a href="{% url "registration:add_organizer" %}" class="btn btn-block btn-secondary">
             <i class="fas fa-user-plus"></i> {% trans "Add organizer" %}
         </a>
diff --git a/locale/fr/LC_MESSAGES/django.po b/locale/fr/LC_MESSAGES/django.po
index fcf26f4..2799919 100644
--- a/locale/fr/LC_MESSAGES/django.po
+++ b/locale/fr/LC_MESSAGES/django.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: TFJM\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2021-01-23 21:55+0100\n"
+"POT-Creation-Date: 2021-02-07 17:38+0100\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: Yohann D'ANELLO <yohann.danello@animath.fr>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -104,51 +104,59 @@ msgstr "Changelog de type \"{action}\" pour le modèle {model} le {timestamp}"
 msgid "valid"
 msgstr "valide"
 
-#: apps/participation/forms.py:23 apps/participation/models.py:41
+#: apps/participation/forms.py:24
+msgid "This name is already used."
+msgstr "Ce nom est déjà utilisé."
+
+#: apps/participation/forms.py:31 apps/participation/models.py:41
 msgid "The trigram must be composed of three uppercase letters."
 msgstr "Le trigramme doit être composé de trois lettres majuscules."
 
-#: apps/participation/forms.py:38
+#: apps/participation/forms.py:34
+msgid "This trigram is already used."
+msgstr "Ce trigramme est déjà utilisé."
+
+#: apps/participation/forms.py:49
 msgid "No team was found with this access code."
 msgstr "Aucune équipe n'a été trouvée avec ce code d'accès."
 
-#: apps/participation/forms.py:67 apps/participation/forms.py:202
-#: apps/registration/forms.py:116 apps/registration/forms.py:138
-#: apps/registration/forms.py:160 apps/registration/forms.py:214
+#: apps/participation/forms.py:78 apps/participation/forms.py:213
+#: apps/registration/forms.py:117 apps/registration/forms.py:139
+#: apps/registration/forms.py:161 apps/registration/forms.py:215
 msgid "The uploaded file size must be under 2 Mo."
 msgstr "Le fichier envoyé doit peser moins de 2 Mo."
 
-#: apps/participation/forms.py:69 apps/registration/forms.py:118
-#: apps/registration/forms.py:140 apps/registration/forms.py:162
-#: apps/registration/forms.py:216
+#: apps/participation/forms.py:80 apps/registration/forms.py:119
+#: apps/registration/forms.py:141 apps/registration/forms.py:163
+#: apps/registration/forms.py:217
 msgid "The uploaded file must be a PDF, PNG of JPEG file."
 msgstr "Le fichier envoyé doit être au format PDF, PNG ou JPEG."
 
-#: apps/participation/forms.py:87
+#: apps/participation/forms.py:98
 msgid "I engage myself to participate to the whole TFJM²."
 msgstr "Je m'engage à participer à l'intégralité du TFJM²."
 
-#: apps/participation/forms.py:102
+#: apps/participation/forms.py:113
 msgid "Message to address to the team:"
 msgstr "Message à adresser à l'équipe :"
 
-#: apps/participation/forms.py:139
+#: apps/participation/forms.py:150
 msgid "The uploaded file size must be under 5 Mo."
 msgstr "Le fichier envoyé doit peser moins de 5 Mo."
 
-#: apps/participation/forms.py:141 apps/participation/forms.py:204
+#: apps/participation/forms.py:152 apps/participation/forms.py:215
 msgid "The uploaded file must be a PDF file."
 msgstr "Le fichier envoyé doit être au format PDF."
 
-#: apps/participation/forms.py:145
+#: apps/participation/forms.py:156
 msgid "The PDF file must not have more than 30 pages."
 msgstr "Le fichier PDF ne doit pas avoir plus de 30 pages."
 
-#: apps/participation/forms.py:185
+#: apps/participation/forms.py:196
 msgid "The defender, the opponent and the reporter must be different."
 msgstr "Le défenseur, l'opposant et le rapporteur doivent être différents."
 
-#: apps/participation/forms.py:189
+#: apps/participation/forms.py:200
 msgid "This defender did not work on this problem."
 msgstr "Ce défenseur ne travaille pas sur ce problème."
 
@@ -506,12 +514,12 @@ msgstr ""
 
 #: apps/participation/templates/participation/create_team.html:11
 #: apps/participation/templates/participation/tournament_form.html:14
-#: tfjm/templates/base.html:240
+#: tfjm/templates/base.html:234
 msgid "Create"
 msgstr "Créer"
 
 #: apps/participation/templates/participation/join_team.html:11
-#: tfjm/templates/base.html:235
+#: tfjm/templates/base.html:229
 msgid "Join"
 msgstr "Rejoindre"
 
@@ -529,8 +537,7 @@ msgstr "Rejoindre"
 #: apps/registration/templates/registration/payment_form.html:49
 #: apps/registration/templates/registration/update_user.html:16
 #: apps/registration/templates/registration/user_detail.html:153
-#: apps/registration/templates/registration/user_detail.html:162
-#: apps/registration/templates/registration/user_detail.html:190
+#: apps/registration/templates/registration/user_detail.html:185
 msgid "Update"
 msgstr "Modifier"
 
@@ -586,10 +593,10 @@ msgstr "Envoyer une solution"
 #: apps/registration/templates/registration/upload_health_sheet.html:17
 #: apps/registration/templates/registration/upload_parental_authorization.html:17
 #: apps/registration/templates/registration/upload_photo_authorization.html:18
+#: apps/registration/templates/registration/user_detail.html:163
 #: apps/registration/templates/registration/user_detail.html:168
 #: apps/registration/templates/registration/user_detail.html:173
 #: apps/registration/templates/registration/user_detail.html:178
-#: apps/registration/templates/registration/user_detail.html:183
 msgid "Upload"
 msgstr "Téléverser"
 
@@ -824,8 +831,8 @@ msgid ""
 "Your team must be composed of 4 members and a coach and each member must "
 "upload their authorizations and confirm its email address."
 msgstr ""
-"Votre équipe doit être composée d'au moins 4 membres et un encadrant et chaque "
-"membre doit envoyer ses autorisations et confirmé son adresse e-mail."
+"Votre équipe doit être composée d'au moins 4 membres et un encadrant et "
+"chaque membre doit envoyer ses autorisations et confirmé son adresse e-mail."
 
 #: apps/participation/templates/participation/team_detail.html:146
 msgid "This team didn't ask for validation yet."
@@ -852,7 +859,7 @@ msgid "Invalidate"
 msgstr "Invalider"
 
 #: apps/participation/templates/participation/team_detail.html:169
-#: apps/participation/views.py:323
+#: apps/participation/views.py:324
 msgid "Upload motivation letter"
 msgstr "Envoyer la lettre de motivation"
 
@@ -861,7 +868,7 @@ msgid "Update team"
 msgstr "Modifier l'équipe"
 
 #: apps/participation/templates/participation/team_detail.html:179
-#: apps/participation/views.py:424
+#: apps/participation/views.py:425
 msgid "Leave team"
 msgstr "Quitter l'équipe"
 
@@ -870,7 +877,7 @@ msgid "Are you sure that you want to leave this team?"
 msgstr "Êtes-vous sûr·e de vouloir quitter cette équipe ?"
 
 #: apps/participation/templates/participation/team_list.html:6
-#: tfjm/templates/base.html:228
+#: tfjm/templates/base.html:222
 msgid "All teams"
 msgstr "Toutes les équipes"
 
@@ -953,7 +960,7 @@ msgid "Add pool"
 msgstr "Ajouter une poule"
 
 #: apps/participation/templates/participation/tournament_list.html:6
-#: tfjm/templates/base.html:224
+#: tfjm/templates/base.html:218
 msgid "All tournaments"
 msgstr "Tous les tournois"
 
@@ -966,7 +973,7 @@ msgid "Back to the team detail"
 msgstr "Retour aux détails de l'utilisateur"
 
 #: apps/participation/views.py:43 tfjm/templates/base.html:74
-#: tfjm/templates/base.html:239
+#: tfjm/templates/base.html:233
 msgid "Create team"
 msgstr "Créer une équipe"
 
@@ -979,16 +986,16 @@ msgid "You are already in a team."
 msgstr "Vous êtes déjà dans une équipe."
 
 #: apps/participation/views.py:88 tfjm/templates/base.html:79
-#: tfjm/templates/base.html:234
+#: tfjm/templates/base.html:228
 msgid "Join team"
 msgstr "Rejoindre une équipe"
 
-#: apps/participation/views.py:150 apps/participation/views.py:430
-#: apps/participation/views.py:463
+#: apps/participation/views.py:150 apps/participation/views.py:431
+#: apps/participation/views.py:464
 msgid "You are not in a team."
 msgstr "Vous n'êtes pas dans une équipe."
 
-#: apps/participation/views.py:151 apps/participation/views.py:464
+#: apps/participation/views.py:151 apps/participation/views.py:465
 msgid "You don't participate, so you don't have any team."
 msgstr "Vous ne participez pas, vous n'avez donc pas d'équipe."
 
@@ -1016,98 +1023,98 @@ msgstr ""
 "d'adresse e-mail, soit une autorisation, soit des personnes, soit la lettre "
 "de motivation, soit le tournoi n'a pas été choisi."
 
-#: apps/participation/views.py:239
+#: apps/participation/views.py:240
 msgid "You are not an organizer of the tournament."
 msgstr "Vous n'êtes pas un organisateur du tournoi."
 
-#: apps/participation/views.py:242
+#: apps/participation/views.py:243
 msgid "This team has no pending validation."
 msgstr "L'équipe n'a pas de validation en attente."
 
-#: apps/participation/views.py:272
+#: apps/participation/views.py:273
 msgid "You must specify if you validate the registration or not."
 msgstr "Vous devez spécifier si vous validez l'inscription ou non."
 
-#: apps/participation/views.py:303
+#: apps/participation/views.py:304
 #, python-brace-format
 msgid "Update team {trigram}"
 msgstr "Mise à jour de l'équipe {trigram}"
 
-#: apps/participation/views.py:361 apps/participation/views.py:410
+#: apps/participation/views.py:362 apps/participation/views.py:411
 #, python-brace-format
 msgid "Motivation letter of {team}.{ext}"
 msgstr "Lettre de motivation de {team}.{ext}"
 
-#: apps/participation/views.py:391
+#: apps/participation/views.py:392
 #, python-brace-format
 msgid "Photo authorization of {participant}.{ext}"
 msgstr "Autorisation de droit à l'image de {participant}.{ext}"
 
-#: apps/participation/views.py:397
+#: apps/participation/views.py:398
 #, python-brace-format
 msgid "Parental authorization of {participant}.{ext}"
 msgstr "Autorisation parentale de {participant}.{ext}"
 
-#: apps/participation/views.py:404
+#: apps/participation/views.py:405
 #, python-brace-format
 msgid "Health sheet of {participant}.{ext}"
 msgstr "Fiche sanitaire de {participant}.{ext}"
 
-#: apps/participation/views.py:414
+#: apps/participation/views.py:415
 #, python-brace-format
 msgid "Photo authorizations of team {trigram}.zip"
 msgstr "Autorisations de droit à l'image de l'équipe {trigram}.zip"
 
-#: apps/participation/views.py:432
+#: apps/participation/views.py:433
 msgid "The team is already validated or the validation is pending."
 msgstr "La validation de l'équipe est déjà faite ou en cours."
 
-#: apps/participation/views.py:478
+#: apps/participation/views.py:479
 msgid "The team is not validated yet."
 msgstr "L'équipe n'est pas encore validée."
 
-#: apps/participation/views.py:490
+#: apps/participation/views.py:491
 #, python-brace-format
 msgid "Participation of team {trigram}"
 msgstr "Participation de l'équipe {trigram}"
 
-#: apps/participation/views.py:579
+#: apps/participation/views.py:580
 msgid "You can't upload a solution after the deadline."
 msgstr "Vous ne pouvez pas envoyer de solution après la date limite."
 
-#: apps/participation/views.py:760
+#: apps/participation/views.py:761
 msgid "You can't upload a synthesis after the deadline."
 msgstr "Vous ne pouvez pas envoyer de note de synthèse après la date limite."
 
-#: apps/registration/forms.py:21 apps/registration/forms.py:53
+#: apps/registration/forms.py:22 apps/registration/forms.py:54
 msgid "role"
 msgstr "rôle"
 
-#: apps/registration/forms.py:23
+#: apps/registration/forms.py:24
 msgid "participant"
 msgstr "participant"
 
-#: apps/registration/forms.py:24 apps/registration/models.py:259
+#: apps/registration/forms.py:25 apps/registration/models.py:259
 msgid "coach"
 msgstr "encadrant"
 
-#: apps/registration/forms.py:34 apps/registration/forms.py:67
+#: apps/registration/forms.py:35 apps/registration/forms.py:68
 msgid "This email address is already used."
 msgstr "Cette adresse e-mail est déjà utilisée."
 
-#: apps/registration/forms.py:55 apps/registration/models.py:285
+#: apps/registration/forms.py:56 apps/registration/models.py:285
 msgid "volunteer"
 msgstr "bénévole"
 
-#: apps/registration/forms.py:56 apps/registration/models.py:304
+#: apps/registration/forms.py:57 apps/registration/models.py:304
 msgid "admin"
 msgstr "admin"
 
-#: apps/registration/forms.py:208
+#: apps/registration/forms.py:209
 msgid "Pending"
 msgstr "En attente"
 
-#: apps/registration/forms.py:224
+#: apps/registration/forms.py:225
 msgid "You must upload your scholarship attestation."
 msgstr "Vous devez envoyer votre attestation de bourse."
 
@@ -1407,8 +1414,8 @@ msgid "Your password has been set. You may go ahead and log in now."
 msgstr "Votre mot de passe a été changé. Vous pouvez désormais vous connecter."
 
 #: apps/registration/templates/registration/password_reset_complete.html:10
-#: tfjm/templates/base.html:127 tfjm/templates/base.html:244
-#: tfjm/templates/base.html:245 tfjm/templates/registration/login.html:7
+#: tfjm/templates/base.html:127 tfjm/templates/base.html:238
+#: tfjm/templates/base.html:239 tfjm/templates/registration/login.html:7
 #: tfjm/templates/registration/login.html:8
 #: tfjm/templates/registration/login.html:25
 msgid "Log in"
@@ -1645,7 +1652,7 @@ msgid "valid:"
 msgstr "valide :"
 
 #: apps/registration/templates/registration/user_detail.html:136
-#: apps/registration/templates/registration/user_detail.html:189
+#: apps/registration/templates/registration/user_detail.html:184
 msgid "Update payment"
 msgstr "Modifier le paiement"
 
@@ -1657,22 +1664,18 @@ msgstr "Télécharger l'attestation de bourse"
 msgid "Impersonate"
 msgstr "Impersonifier"
 
-#: apps/registration/templates/registration/user_detail.html:161
-msgid "Update user"
-msgstr "Modifier l'utilisateur"
-
-#: apps/registration/templates/registration/user_detail.html:167
+#: apps/registration/templates/registration/user_detail.html:162
 #: apps/registration/views.py:313
 msgid "Upload photo authorization"
 msgstr "Téléverser l'autorisation de droit à l'image"
 
-#: apps/registration/templates/registration/user_detail.html:172
+#: apps/registration/templates/registration/user_detail.html:167
 #: apps/registration/views.py:334
 msgid "Upload health sheet"
 msgstr "Téléverser la fiche sanitaire"
 
+#: apps/registration/templates/registration/user_detail.html:172
 #: apps/registration/templates/registration/user_detail.html:177
-#: apps/registration/templates/registration/user_detail.html:182
 #: apps/registration/views.py:355
 msgid "Upload parental authorization"
 msgstr "Téléverser l'autorisation parentale"
@@ -1711,22 +1714,22 @@ msgstr "Détails de l'utilisateur {user}"
 msgid "Update user {user}"
 msgstr "Mise à jour de l'utilisateur {user}"
 
-#: apps/registration/views.py:459
+#: apps/registration/views.py:461
 #, python-brace-format
 msgid "Photo authorization of {student}.{ext}"
 msgstr "Autorisation de droit à l'image de {student}.{ext}"
 
-#: apps/registration/views.py:482
+#: apps/registration/views.py:484
 #, python-brace-format
 msgid "Health sheet of {student}.{ext}"
 msgstr "Fiche sanitaire de {student}.{ext}"
 
-#: apps/registration/views.py:505
+#: apps/registration/views.py:507
 #, python-brace-format
 msgid "Parental authorization of {student}.{ext}"
 msgstr "Autorisation parentale de {student}.{ext}"
 
-#: apps/registration/views.py:527
+#: apps/registration/views.py:529
 #, python-brace-format
 msgid "Scholarship attestation of {user}.{ext}"
 msgstr "Notification de bourse de {user}.{ext}"
@@ -1851,15 +1854,15 @@ msgstr ""
 "avez reçu par mail. Vous pouvez renvoyer un mail en cliquant sur <a href="
 "\"%(send_email_url)s\">ce lien</a>."
 
-#: tfjm/templates/base.html:189
+#: tfjm/templates/base.html:183
 msgid "Contact us"
 msgstr "Nous contacter"
 
-#: tfjm/templates/base.html:208
+#: tfjm/templates/base.html:202
 msgid "About"
 msgstr "À propos"
 
-#: tfjm/templates/base.html:231
+#: tfjm/templates/base.html:225
 msgid "Search results"
 msgstr "Résultats de la recherche"
 
@@ -1895,3 +1898,6 @@ msgstr "Résultats"
 #: tfjm/templates/search/search.html:25
 msgid "No results found."
 msgstr "Aucun résultat."
+
+#~ msgid "Update user"
+#~ msgstr "Modifier l'utilisateur"
diff --git a/tfjm/templates/base.html b/tfjm/templates/base.html
index 85c2744..1c588d4 100644
--- a/tfjm/templates/base.html
+++ b/tfjm/templates/base.html
@@ -162,13 +162,7 @@
                 {% endblocktrans %}
             </div>
         {% endif %}
-        <div id="messages">
-            <div class="alert alert-success">
-                Les inscriptions sont désormais ouvertes ! Si jamais vous aviez essayé de vous inscrire le 22 janvier,
-                il est possible que votre compte ait été supprimé. Vous pouvez désormais le recréer. Merci pour votre
-                patience, et bon TFJM² ! :)
-            </div>
-        </div>
+        <div id="messages"></div>
         <div id="content">
             {% block content %}
                 <p>Default content...</p>
diff --git a/tfjm/templates/index.html b/tfjm/templates/index.html
index 635885d..3d9e588 100644
--- a/tfjm/templates/index.html
+++ b/tfjm/templates/index.html
@@ -3,6 +3,24 @@
 {% block content %}
     <div>
 
+    <div class="alert alert-warning">
+        <p>
+            Certains d'entre vous rencontrent des difficultés lors de l'inscription. Quelques points :
+            <ul>
+                <li>Tout d'abord, il est inutile de créer plusieurs comptes.</li>
+                <li>Si vous ne recevez pas le mail de validation de l'adresse mail, vous pouvez quand même vous connecter.
+                    Vous pourrez via un lien redemander un mail. Merci de ne pas spammer ce bouton toutefois. Pensez à vérifier
+                    vos spams. Contactez-nous si vous ne recevez toujours rien.</li>
+                <li>Les différentes autorisations sont à soumettre sur la page de votre compte.</li>
+                <li>La date limite d'inscription est fixée en général à un mois avant le début du tournoi, soit début mars.
+                    Le site <a href="https://tfjm.org/">https://tfjm.org/</a> sera mis à jour dans les jours qui suivent.</li>
+            </ul>
+        </p>
+        <p>
+            Une documentation plus complète sera disponible dans les jours à venir et régulièrement mise à jour pour apprendre à utiliser la plateforme.
+        </p>
+    </div>
+
     <div class="jumbotron bg-white">
         <div class="row">
             <h1 class="display-3">