diff --git a/anymail/backends/mailersend.py b/anymail/backends/mailersend.py
index f9af9ae..04f3043 100644
--- a/anymail/backends/mailersend.py
+++ b/anymail/backends/mailersend.py
@@ -155,8 +155,8 @@ class MailerSendPayload(RequestsPayload):
                 # We can't guess which API to use for this send.
                 raise AnymailUnsupportedFeature(
                     f"{self.esp_name} requires MAILERSEND_BATCH_SEND_MODE set to either"
-                    f" 'use-bulk-email' or 'expose-to-list' for using batch send"
-                    f" (merge_data) with multiple recipients. See the Anymail docs."
+                    " 'use-bulk-email' or 'expose-to-list' for using batch send"
+                    " (merge_data) with multiple recipients. See the Anymail docs."
                 )
         else:
             return "email"
@@ -184,7 +184,7 @@ class MailerSendPayload(RequestsPayload):
                 data.append(recipient_data)
         else:
             raise AssertionError(
-                f"MailerSendPayload.serialize_data missing"
+                "MailerSendPayload.serialize_data missing"
                 f" case for api_endpoint {api_endpoint!r}"
             )
         return self.serialize_json(data)
diff --git a/anymail/webhooks/brevo.py b/anymail/webhooks/brevo.py
index 1462728..cb07f59 100644
--- a/anymail/webhooks/brevo.py
+++ b/anymail/webhooks/brevo.py
@@ -35,7 +35,7 @@ class BrevoTrackingWebhookView(BrevoBaseWebhookView):
         if "items" in esp_event:
             # This is an inbound webhook post
             raise AnymailConfigurationError(
-                f"You seem to have set Brevo's *inbound* webhook URL "
+                "You seem to have set Brevo's *inbound* webhook URL "
                 f"to Anymail's {self.esp_name} *tracking* webhook URL."
             )
         return [self.esp_to_anymail_event(esp_event)]
@@ -156,7 +156,7 @@ class BrevoInboundWebhookView(BrevoBaseWebhookView):
         except KeyError:
             # This is not an inbound webhook post
             raise AnymailConfigurationError(
-                f"You seem to have set Brevo's *tracking* webhook URL "
+                "You seem to have set Brevo's *tracking* webhook URL "
                 f"to Anymail's {self.esp_name} *inbound* webhook URL."
             )
         else:
diff --git a/anymail/webhooks/mailersend.py b/anymail/webhooks/mailersend.py
index a89439f..cbaa2f4 100644
--- a/anymail/webhooks/mailersend.py
+++ b/anymail/webhooks/mailersend.py
@@ -52,7 +52,7 @@ class MailerSendBaseWebhookView(AnymailBaseWebhookView):
         ).hexdigest()
         if not constant_time_compare(signature, expected_signature):
             raise AnymailWebhookValidationFailure(
-                f"MailerSend webhook called with incorrect signature"
+                "MailerSend webhook called with incorrect signature"
                 f" (check Anymail {self._secret_setting_name} setting)"
             )
 
diff --git a/anymail/webhooks/postmark.py b/anymail/webhooks/postmark.py
index bbc53e6..f8a2952 100644
--- a/anymail/webhooks/postmark.py
+++ b/anymail/webhooks/postmark.py
@@ -166,7 +166,7 @@ class PostmarkInboundWebhookView(PostmarkBaseWebhookView):
         if esp_record_type != "Inbound":
             raise AnymailConfigurationError(
                 f"You seem to have set Postmark's *{esp_record_type}* webhook"
-                f" to Anymail's Postmark *inbound* webhook URL."
+                " to Anymail's Postmark *inbound* webhook URL."
             )
 
         headers = esp_event.get("Headers", [])