diff --git a/src/configure/mod.rs b/src/configure/mod.rs
index 841553e58..8783fd30e 100644
--- a/src/configure/mod.rs
+++ b/src/configure/mod.rs
@@ -24,7 +24,7 @@ use crate::{chat, e2ee, provider};
 
 use auto_mozilla::moz_autoconfigure;
 use auto_outlook::outlk_autodiscover;
-use server_params::ServerParams;
+use server_params::{expand_param_vector, ServerParams};
 
 macro_rules! progress {
     ($context:tt, $progress:expr) => {
@@ -194,8 +194,8 @@ async fn configure(ctx: &Context, param: &mut LoginParam) -> Result<()> {
 
     progress!(ctx, 500);
 
-    let servers: Vec<ServerParams> = param_autoconfig
-        .unwrap_or_else(|| {
+    let servers = expand_param_vector(
+        param_autoconfig.unwrap_or_else(|| {
             vec![
                 ServerParams {
                     protocol: Protocol::IMAP,
@@ -212,16 +212,10 @@ async fn configure(ctx: &Context, param: &mut LoginParam) -> Result<()> {
                     username: param.smtp.user.clone(),
                 },
             ]
-        })
-        .into_iter()
-        // The order of expansion is important: ports are expanded the
-        // last, so they are changed the first. Username is only
-        // changed if default value (address with domain) didn't work
-        // for all available hosts and ports.
-        .flat_map(|params| params.expand_usernames(&param.addr).into_iter())
-        .flat_map(|params| params.expand_hostnames(&param_domain).into_iter())
-        .flat_map(|params| params.expand_ports().into_iter())
-        .collect();
+        }),
+        &param.addr,
+        &param_domain,
+    );
 
     progress!(ctx, 600);
 
diff --git a/src/configure/server_params.rs b/src/configure/server_params.rs
index 4f533d918..df577de60 100644
--- a/src/configure/server_params.rs
+++ b/src/configure/server_params.rs
@@ -6,7 +6,7 @@ use crate::provider::{Protocol, Socket};
 ///
 /// Can be loaded from offline provider database, online configuraiton
 /// or derived from user entered parameters.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub(crate) struct ServerParams {
     /// Protocol, such as IMAP or SMTP.
     pub protocol: Protocol,
@@ -113,3 +113,52 @@ impl ServerParams {
         res
     }
 }
+
+/// Expands vector of `ServerParams`, replacing placeholders with
+/// variants to try.
+pub(crate) fn expand_param_vector(
+    v: Vec<ServerParams>,
+    addr: &str,
+    domain: &str,
+) -> Vec<ServerParams> {
+    v.into_iter()
+        // The order of expansion is important: ports are expanded the
+        // last, so they are changed the first. Username is only
+        // changed if default value (address with domain) didn't work
+        // for all available hosts and ports.
+        .flat_map(|params| params.expand_usernames(addr).into_iter())
+        .flat_map(|params| params.expand_hostnames(domain).into_iter())
+        .flat_map(|params| params.expand_ports().into_iter())
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_expand_param_vector() {
+        let v = expand_param_vector(
+            vec![ServerParams {
+                protocol: Protocol::IMAP,
+                hostname: "example.net".to_string(),
+                port: 0,
+                socket: Socket::SSL,
+                username: "foobar".to_string(),
+            }],
+            "foobar@example.net",
+            "example.net",
+        );
+
+        assert_eq!(
+            v,
+            vec![ServerParams {
+                protocol: Protocol::IMAP,
+                hostname: "example.net".to_string(),
+                port: 993,
+                socket: Socket::SSL,
+                username: "foobar".to_string(),
+            }],
+        );
+    }
+}