diff --git a/crates/smtp/src/config/auth.rs b/crates/smtp/src/config/auth.rs
index 8ff6b2c6..2c976e3b 100644
--- a/crates/smtp/src/config/auth.rs
+++ b/crates/smtp/src/config/auth.rs
@@ -235,17 +235,20 @@ impl ConfigAuth for Config {
                             })?;
                         }
 
-                        let key = Ed25519Key::from_seed_and_public_key(&private_key, &public_key)
+                        let key = Ed25519Key::from_pkcs8_maybe_unchecked_der(&private_key)
+                            .or_else(|_| {
+                                Ed25519Key::from_seed_and_public_key(&private_key, &public_key)
+                            })
                             .map_err(|err| {
-                            format!("Failed to build ED25519 key for signature {id:?}: {err}")
-                        })?;
-                        let key_clone =
-                            Ed25519Key::from_seed_and_public_key(&private_key, &public_key)
-                                .map_err(|err| {
-                                    format!(
-                                        "Failed to build ED25519 key for signature {id:?}: {err}"
-                                    )
-                                })?;
+                                format!("Failed to build ED25519 key for signature {id:?}: {err}")
+                            })?;
+                        let key_clone = Ed25519Key::from_pkcs8_maybe_unchecked_der(&private_key)
+                            .or_else(|_| {
+                                Ed25519Key::from_seed_and_public_key(&private_key, &public_key)
+                            })
+                            .map_err(|err| {
+                                format!("Failed to build ED25519 key for signature {id:?}: {err}")
+                            })?;
 
                         let (signer, sealer) = parse_signature(self, id, key_clone, key)?;
                         (
diff --git a/tests/resources/test_config.toml b/tests/resources/test_config.toml
index e61095ea..f6b9a1ed 100644
--- a/tests/resources/test_config.toml
+++ b/tests/resources/test_config.toml
@@ -198,3 +198,29 @@ allow-plain-text = true
 [imap.rate-limit]
 requests = "90000/1s"
 concurrent = 9000
+
+[signature."ed25519"]
+public-key = "-----BEGIN PUBLIC KEY-----
+MCowBQYDK2VwAyEAUA3S0BdVG7LeA1agv7ZtqLkQMn+/AoYx1VPyGmLWEIM=
+-----END PUBLIC KEY-----"
+private-key = "-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIPdRszAzLvx4JaSIE4dQdZtN9y2XW+55K+YkCJI6lcn8
+-----END PRIVATE KEY-----"
+domain = "example.org"
+selector = "stalwart_ed"
+headers = ["From", "To", "Date", "Subject", "Message-ID"]
+algorithm = "ed25519-sha256"
+canonicalization = "simple/simple"
+set-body-length = true
+report = true
+
+[signature."ed25519-2"]
+public-key = "11qYAYKxCrfVS/7TyWQHOg7hcvPapiMlrwIaaPcHURo="
+private-key = "nWGxne/9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A="
+domain = "example.org"
+selector = "stalwart_ed2"
+headers = ["From", "To", "Date", "Subject", "Message-ID"]
+algorithm = "ed25519-sha256"
+canonicalization = "simple/simple"
+set-body-length = true
+report = true