diff --git a/src/core/changes.rs b/src/core/changes.rs
index 0d3356d..0884747 100644
--- a/src/core/changes.rs
+++ b/src/core/changes.rs
@@ -68,6 +68,10 @@ impl<O: ChangesObject> ChangesResponse<O> {
         &self.account_id
     }
 
+    pub fn unwrap_account_id(self) -> String {
+        self.account_id
+    }
+
     pub fn old_state(&self) -> &str {
         &self.old_state
     }
@@ -76,6 +80,10 @@ impl<O: ChangesObject> ChangesResponse<O> {
         &self.new_state
     }
 
+    pub fn unwrap_new_state(self) -> String {
+        self.new_state
+    }
+
     pub fn has_more_changes(&self) -> bool {
         self.has_more_changes
     }
@@ -95,4 +103,8 @@ impl<O: ChangesObject> ChangesResponse<O> {
     pub fn arguments(&self) -> &O::ChangesResponse {
         &self.arguments
     }
+
+    pub fn total_changes(&self) -> usize {
+        self.created.len() + self.updated.len() + self.destroyed.len()
+    }
 }
diff --git a/src/core/get.rs b/src/core/get.rs
index f541edf..669291a 100644
--- a/src/core/get.rs
+++ b/src/core/get.rs
@@ -103,14 +103,18 @@ impl<O: GetObject> GetRequest<O> {
 }
 
 impl<O> GetResponse<O> {
-    pub fn account_id(&self) -> &str {
-        self.account_id.as_ref().unwrap()
+    pub fn account_id(&self) -> Option<&str> {
+        self.account_id.as_deref()
     }
 
     pub fn state(&self) -> &str {
         &self.state
     }
 
+    pub fn unwrap_state(&mut self) -> String {
+        std::mem::take(&mut self.state)
+    }
+
     pub fn list(&self) -> &[O] {
         &self.list
     }
diff --git a/src/core/response.rs b/src/core/response.rs
index fbcba70..94814d2 100644
--- a/src/core/response.rs
+++ b/src/core/response.rs
@@ -64,8 +64,8 @@ impl<T> Response<T> {
         self.method_responses.remove(index)
     }
 
-    pub fn pop_method_response(&mut self) -> T {
-        self.method_responses.pop().unwrap()
+    pub fn pop_method_response(&mut self) -> Option<T> {
+        self.method_responses.pop()
     }
 
     pub fn created_ids(&self) -> Option<impl Iterator<Item = (&String, &String)>> {
diff --git a/src/core/set.rs b/src/core/set.rs
index 7fb41a1..739387f 100644
--- a/src/core/set.rs
+++ b/src/core/set.rs
@@ -222,16 +222,16 @@ impl<O: SetObject> SetRequest<O> {
 }
 
 impl<O: SetObject> SetResponse<O> {
-    pub fn account_id(&self) -> &str {
-        self.account_id.as_ref().unwrap()
+    pub fn account_id(&self) -> Option<&str> {
+        self.account_id.as_deref()
     }
 
     pub fn old_state(&self) -> Option<&str> {
         self.old_state.as_deref()
     }
 
-    pub fn new_state(&self) -> &str {
-        self.new_state.as_ref().unwrap()
+    pub fn new_state(&self) -> Option<&str> {
+        self.new_state.as_deref()
     }
 
     pub fn created(&mut self, id: &str) -> crate::Result<O> {
diff --git a/src/email/get.rs b/src/email/get.rs
index 702b7a9..a8ec751 100644
--- a/src/email/get.rs
+++ b/src/email/get.rs
@@ -6,48 +6,52 @@ use super::{
 };
 
 impl Email<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
         self.id.unwrap()
     }
 
-    pub fn blob_id(&self) -> &str {
-        self.blob_id.as_ref().unwrap()
+    pub fn blob_id(&self) -> Option<&str> {
+        self.blob_id.as_deref()
     }
 
     pub fn unwrap_blob_id(self) -> String {
         self.blob_id.unwrap()
     }
 
-    pub fn thread_id(&self) -> &str {
-        self.thread_id.as_ref().unwrap()
+    pub fn thread_id(&self) -> Option<&str> {
+        self.thread_id.as_deref()
     }
 
     pub fn mailbox_ids(&self) -> Vec<&str> {
         self.mailbox_ids
             .as_ref()
-            .unwrap()
-            .iter()
-            .filter(|(_, v)| **v)
-            .map(|(k, _)| k.as_str())
-            .collect()
+            .map(|m| {
+                m.iter()
+                    .filter(|(_, v)| **v)
+                    .map(|(k, _)| k.as_str())
+                    .collect()
+            })
+            .unwrap_or_default()
     }
 
     pub fn keywords(&self) -> Vec<&str> {
         self.keywords
             .as_ref()
-            .unwrap()
-            .iter()
-            .filter(|(_, v)| **v)
-            .map(|(k, _)| k.as_str())
-            .collect()
+            .map(|k| {
+                k.iter()
+                    .filter(|(_, v)| **v)
+                    .map(|(k, _)| k.as_str())
+                    .collect()
+            })
+            .unwrap_or_default()
     }
 
     pub fn size(&self) -> usize {
-        self.size.unwrap()
+        self.size.unwrap_or(0)
     }
 
     pub fn received_at(&self) -> Option<i64> {
diff --git a/src/email_submission/get.rs b/src/email_submission/get.rs
index 6a2926c..85fbbb6 100644
--- a/src/email_submission/get.rs
+++ b/src/email_submission/get.rs
@@ -5,24 +5,24 @@ use crate::{core::get::GetObject, Get, Set};
 use super::{Address, Delivered, DeliveryStatus, Displayed, EmailSubmission, UndoStatus};
 
 impl EmailSubmission<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
         self.id.unwrap()
     }
 
-    pub fn identity_id(&self) -> &str {
-        self.identity_id.as_ref().unwrap()
+    pub fn identity_id(&self) -> Option<&str> {
+        self.identity_id.as_deref()
     }
 
-    pub fn email_id(&self) -> &str {
-        self.email_id.as_ref().unwrap()
+    pub fn email_id(&self) -> Option<&str> {
+        self.email_id.as_deref()
     }
 
-    pub fn thread_id(&self) -> &str {
-        self.thread_id.as_ref().unwrap()
+    pub fn thread_id(&self) -> Option<&str> {
+        self.thread_id.as_deref()
     }
 
     pub fn mail_from(&self) -> Option<&Address> {
@@ -33,12 +33,12 @@ impl EmailSubmission<Get> {
         self.envelope.as_ref().map(|e| e.rcpt_to.as_ref())
     }
 
-    pub fn send_at(&self) -> i64 {
-        self.send_at.as_ref().unwrap().timestamp()
+    pub fn send_at(&self) -> Option<i64> {
+        self.send_at.as_ref().map(|t| t.timestamp())
     }
 
-    pub fn undo_status(&self) -> &UndoStatus {
-        self.undo_status.as_ref().unwrap()
+    pub fn undo_status(&self) -> Option<&UndoStatus> {
+        self.undo_status.as_ref()
     }
 
     pub fn delivery_status_email(&self, email: &str) -> Option<&DeliveryStatus> {
diff --git a/src/identity/get.rs b/src/identity/get.rs
index 5715af3..c436e71 100644
--- a/src/identity/get.rs
+++ b/src/identity/get.rs
@@ -3,8 +3,8 @@ use crate::{core::get::GetObject, email::EmailAddress, Get, Set};
 use super::Identity;
 
 impl Identity<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
@@ -15,8 +15,8 @@ impl Identity<Get> {
         self.name.as_deref()
     }
 
-    pub fn email(&self) -> &str {
-        self.email.as_ref().unwrap()
+    pub fn email(&self) -> Option<&str> {
+        self.email.as_deref()
     }
 
     pub fn reply_to(&self) -> Option<&[EmailAddress]> {
diff --git a/src/lib.rs b/src/lib.rs
index 6bf7ced..cd620d5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -226,12 +226,12 @@ impl Display for Error {
             Error::Transport(e) => write!(f, "Transport error: {}", e),
             Error::Parse(e) => write!(f, "Parse error: {}", e),
             Error::Internal(e) => write!(f, "Internal error: {}", e),
-            Error::Problem(e) => write!(f, "Problem details: {}", e),
-            Error::Server(e) => write!(f, "Server error: {}", e),
-            Error::Method(e) => write!(f, "Method error: {}", e),
-            Error::Set(e) => write!(f, "Set error: {}", e),
+            Error::Problem(e) => write!(f, "Request failed: {}", e),
+            Error::Server(e) => write!(f, "Server failed: {}", e),
+            Error::Method(e) => write!(f, "Request failed: {}", e),
+            Error::Set(e) => write!(f, "Set failed: {}", e),
             #[cfg(feature = "websockets")]
-            Error::WebSocket(e) => write!(f, "WebSocket error: {}", e),
+            Error::WebSocket(e) => write!(f, "WebSockets error: {}", e),
         }
     }
 }
diff --git a/src/mailbox/get.rs b/src/mailbox/get.rs
index fe80859..92a9d47 100644
--- a/src/mailbox/get.rs
+++ b/src/mailbox/get.rs
@@ -5,8 +5,8 @@ use crate::{core::get::GetObject, principal::ACL, Get, Set};
 use super::{Mailbox, MailboxRights, Role};
 
 impl Mailbox<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
diff --git a/src/mailbox/mod.rs b/src/mailbox/mod.rs
index d1398f0..4bfdbe1 100644
--- a/src/mailbox/mod.rs
+++ b/src/mailbox/mod.rs
@@ -116,6 +116,12 @@ pub enum Role {
     None,
 }
 
+impl Default for Role {
+    fn default() -> Self {
+        Role::None
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct MailboxRights {
     #[serde(rename = "mayReadItems")]
@@ -174,6 +180,18 @@ pub enum Property {
     ACL,
 }
 
+impl Property {
+    pub fn is_count(&self) -> bool {
+        matches!(
+            self,
+            Property::TotalEmails
+                | Property::UnreadEmails
+                | Property::TotalThreads
+                | Property::UnreadThreads
+        )
+    }
+}
+
 impl Display for Property {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
diff --git a/src/principal/get.rs b/src/principal/get.rs
index 69386b6..a86eb1f 100644
--- a/src/principal/get.rs
+++ b/src/principal/get.rs
@@ -5,8 +5,8 @@ use crate::{core::get::GetObject, Get, Set};
 use super::{Principal, Type, ACL, DKIM};
 
 impl Principal<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
diff --git a/src/push_subscription/get.rs b/src/push_subscription/get.rs
index 3413850..e29047d 100644
--- a/src/push_subscription/get.rs
+++ b/src/push_subscription/get.rs
@@ -1,22 +1,22 @@
-use crate::{core::get::GetObject, Get, TypeState, Set};
+use crate::{core::get::GetObject, Get, Set, TypeState};
 
 use super::{Keys, PushSubscription};
 
 impl PushSubscription<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn unwrap_id(self) -> String {
         self.id.unwrap()
     }
 
-    pub fn device_client_id(&self) -> &str {
-        self.device_client_id.as_ref().unwrap()
+    pub fn device_client_id(&self) -> Option<&str> {
+        self.device_client_id.as_deref()
     }
 
-    pub fn url(&self) -> &str {
-        self.url.as_ref().unwrap()
+    pub fn url(&self) -> Option<&str> {
+        self.url.as_deref()
     }
 
     pub fn keys(&self) -> Option<&Keys> {
diff --git a/src/vacation_response/get.rs b/src/vacation_response/get.rs
index 21b4f69..d59ef2e 100644
--- a/src/vacation_response/get.rs
+++ b/src/vacation_response/get.rs
@@ -3,8 +3,8 @@ use crate::{core::get::GetObject, Get, Set};
 use super::VacationResponse;
 
 impl VacationResponse<Get> {
-    pub fn id(&self) -> &str {
-        self.id.as_ref().unwrap()
+    pub fn id(&self) -> Option<&str> {
+        self.id.as_deref()
     }
 
     pub fn is_enabled(&self) -> bool {