diff --git a/lib/pleroma/emails/mailer.ex b/lib/pleroma/emails/mailer.ex
index 6a79a7694..e4f53f715 100644
--- a/lib/pleroma/emails/mailer.ex
+++ b/lib/pleroma/emails/mailer.ex
@@ -86,6 +86,9 @@ defp default_config(Swoosh.Adapters.SMTP, conf, _) do
       verify: :verify_peer,
       # some versions have supposedly issues verifying wildcard certs without this
       server_name_indication: relay,
+      customize_hostname_check: [
+        match_fun: :public_key.pkix_verify_hostname_match_fun(:https)
+      ],
       # the default of 10 is too restrictive
       depth: 32
     ]