diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 7e551303..d98b99db 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -42,7 +42,7 @@ jobs:
           export TZ=UTC
           poetry --version
           poetry install --extras all
-          poetry run pytest -x
+          poetry run pytest --showlocals
   minversions:
     name: minimum dependency versions
     runs-on: ubuntu-latest
@@ -70,7 +70,7 @@ jobs:
           poetry --version
           poetry lock
           poetry install --extras all
-          poetry run pytest
+          poetry run pytest --showlocals
   style:
     runs-on: ubuntu-latest
     steps:
diff --git a/canaille/app/mails.py b/canaille/app/mails.py
index e2e015e1..81eced5f 100644
--- a/canaille/app/mails.py
+++ b/canaille/app/mails.py
@@ -38,6 +38,16 @@ def logo():
     return logo_cid, logo_filename, logo_raw
 
 
+def type_from_filename(filename):
+    filetype = mimetypes.guess_type(filename)
+    if not filetype or not filetype[0]:  # pragma: no cover
+        # For some reasons GHA fails to guess webp mimetypes
+        return "application", "octet-stream"
+
+    maintype, subtype = filetype[0].split("/")
+    return maintype, subtype
+
+
 def send_email(subject, recipient, text, html, attachements=None):
     current_app.logger.debug(f"Sending a mail to {recipient}: {subject}")
     msg = email.message.EmailMessage()
@@ -58,11 +68,7 @@ def send_email(subject, recipient, text, html, attachements=None):
 
     attachements = attachements or []
     for cid, filename, value in attachements:
-        filetype = mimetypes.guess_type(filename)
-        if not filetype or not filetype[0]:  # pragma: no cover
-            continue
-
-        maintype, subtype = filetype[0].split("/")
+        maintype, subtype = type_from_filename(filename)
         msg.get_payload()[1].add_related(
             value, maintype=maintype, subtype=subtype, cid=cid
         )
diff --git a/canaille/core/endpoints/admin.py b/canaille/core/endpoints/admin.py
index 3bb6e0c7..8a3c6682 100644
--- a/canaille/core/endpoints/admin.py
+++ b/canaille/core/endpoints/admin.py
@@ -39,9 +39,9 @@ def mail_index(user):
     form = MailTestForm(request.form or None)
     if request.form and form.validate():
         if send_test_mail(form.email.data):
-            flash(_("The test invitation mail has been sent correctly"), "success")
+            flash(_("The test mail has been sent correctly"), "success")
         else:
-            flash(_("The test invitation mail has not been sent correctly"), "error")
+            flash(_("The test mail has not been sent correctly"), "error")
 
     return render_template("mails/admin.html", form=form, menuitem="admin")
 
diff --git a/tests/app/test_mails.py b/tests/app/test_mails.py
index ab5c6e7f..7061f592 100644
--- a/tests/app/test_mails.py
+++ b/tests/app/test_mails.py
@@ -23,7 +23,7 @@ def test_send_test_email(testclient, logged_admin, smtpd):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1
@@ -45,7 +45,7 @@ def test_send_test_email_ssl(testclient, logged_admin, smtpd):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1
@@ -62,7 +62,7 @@ def test_send_test_email_without_credentials(testclient, logged_admin, smtpd):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1
@@ -80,7 +80,7 @@ def test_send_test_email_recipient_refused(SMTP, testclient, logged_admin, smtpd
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 0
@@ -94,7 +94,7 @@ def test_send_test_email_failed(testclient, logged_admin):
         res = res.form.submit(expect_errors=True)
     assert (
         "error",
-        "The test invitation mail has not been sent correctly",
+        "The test mail has not been sent correctly",
     ) in res.flashes
 
 
@@ -107,7 +107,7 @@ def test_mail_with_default_no_logo(testclient, logged_admin, smtpd):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1
@@ -129,7 +129,7 @@ def test_mail_with_default_logo(testclient, logged_admin, smtpd, httpserver):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1
@@ -157,7 +157,7 @@ def test_mail_with_logo_in_http(testclient, logged_admin, smtpd, httpserver):
     res = res.form.submit()
     assert (
         "success",
-        "The test invitation mail has been sent correctly",
+        "The test mail has been sent correctly",
     ) in res.flashes
 
     assert len(smtpd.messages) == 1