Configure: Try "imap.*"/"smtp.*"/"mail.*" first (#3207)

* Configure: Try "imap.*"/"smtp.*"/"mail.*" first

Fix half of #3158.

Try "imap.ex.org"/"smtp.ex.org" and "mail.ex.org" first because if a server exists
under this address, it's likely the correct one.

Try "ex.org" last because if it's wrong and the server is configured to
not answer at all, configuration may be stuck for several minutes.

* Changelog

* Add test

CHANGELOG.md

@@ -20,6 +20,7 @@
 - speed up loading of chat messages #3171
 - clear more columns when message expires due to `delete_device_after` setting #3181
 - do not try to use stale SMTP connections #3180
+- Slightly improve finding the correct server after logging in #3207
 - retry message sending automatically if loop is not interrupted #3183
 
 ### Changes

src/configure/server_params.rs

@@ -52,10 +52,8 @@ impl ServerParams {
     fn expand_hostnames(self, param_domain: &str) -> Vec<ServerParams> {
         if self.hostname.is_empty() {
             vec![
-                Self {
-                    hostname: param_domain.to_string(),
-                    ..self.clone()
-                },
+                // Try "imap.ex.org"/"smtp.ex.org" and "mail.ex.org" first because if a server exists
+                // under this address, it's likely the correct one.
                 Self {
                     hostname: match self.protocol {
                         Protocol::Imap => "imap.".to_string() + param_domain,
@@ -65,6 +63,12 @@ impl ServerParams {
                 },
                 Self {
                     hostname: "mail.".to_string() + param_domain,
+                    ..self.clone()
+                },
+                // Try "ex.org" last because if it's wrong and the server is configured to
+                // not answer at all, configuration may be stuck for several minutes.
+                Self {
+                    hostname: param_domain.to_string(),
                     ..self
                 },
             ]
@@ -296,5 +300,48 @@ mod tests {
                 strict_tls: Some(true)
             }],
         );
+
+        // Test that "example.net" is tried after "*.example.net".
+        let v = expand_param_vector(
+            vec![ServerParams {
+                protocol: Protocol::Imap,
+                hostname: "".to_string(),
+                port: 10480,
+                socket: Socket::Ssl,
+                username: "foobar".to_string(),
+                strict_tls: Some(true),
+            }],
+            "foobar@example.net",
+            "example.net",
+        );
+        assert_eq!(
+            v,
+            vec![
+                ServerParams {
+                    protocol: Protocol::Imap,
+                    hostname: "imap.example.net".to_string(),
+                    port: 10480,
+                    socket: Socket::Ssl,
+                    username: "foobar".to_string(),
+                    strict_tls: Some(true)
+                },
+                ServerParams {
+                    protocol: Protocol::Imap,
+                    hostname: "mail.example.net".to_string(),
+                    port: 10480,
+                    socket: Socket::Ssl,
+                    username: "foobar".to_string(),
+                    strict_tls: Some(true)
+                },
+                ServerParams {
+                    protocol: Protocol::Imap,
+                    hostname: "example.net".to_string(),
+                    port: 10480,
+                    socket: Socket::Ssl,
+                    username: "foobar".to_string(),
+                    strict_tls: Some(true)
+                }
+            ],
+        );
     }
 }