diff --git a/examples/main.rs b/examples/main.rs
index f45a553..c3b4ee5 100644
--- a/examples/main.rs
+++ b/examples/main.rs
@@ -4,11 +4,11 @@ use sendgrid::{Destination, Mail};
 fn main() {
     let mut env_vars = std::env::vars();
     let api_key_check = env_vars.find(|var| var.0 == "SENDGRID_API_KEY");
-    let api_key: String;
-    match api_key_check {
-        Some(key) => api_key = key.1,
+
+    let api_key: String = match api_key_check {
+        Some(key) => key.1,
         None => panic!("Must supply API key in environment variables to use!"),
-    }
+    };
 
     let sg = SGClient::new(api_key);
 
diff --git a/examples/v3.rs b/examples/v3.rs
index 964b674..cb53432 100644
--- a/examples/v3.rs
+++ b/examples/v3.rs
@@ -19,7 +19,7 @@ fn main() {
         .add_personalization(p);
 
     let api_key = ::std::env::var("SG_API_KEY").unwrap();
-    let sender = Sender::new(api_key);
+    let sender = Sender::new(api_key, None);
     let code = sender.blocking_send(&m);
     println!("{:?}", code);
 }
diff --git a/examples/v3_async.rs b/examples/v3_async.rs
index df82749..a0eff2a 100644
--- a/examples/v3_async.rs
+++ b/examples/v3_async.rs
@@ -22,7 +22,7 @@ async fn main() -> Result<(), SendgridError> {
 
     let mut env_vars = ::std::env::vars();
     let api_key = env_vars.find(|v| v.0 == "SG_API_KEY").unwrap();
-    let sender = Sender::new(api_key.1);
+    let sender = Sender::new(api_key.1, None);
     let resp = sender.send(&m).await?;
     println!("status: {}", resp.status());
 
diff --git a/examples/v3_disable_tracking.rs b/examples/v3_disable_tracking.rs
index 1bf40cc..38ac0ff 100644
--- a/examples/v3_disable_tracking.rs
+++ b/examples/v3_disable_tracking.rs
@@ -43,7 +43,7 @@ fn main() {
         })
         .add_personalization(person);
 
-    let sender = Sender::new(api_key.to_owned());
+    let sender = Sender::new(api_key.to_owned(), None);
     match sender.blocking_send(&message) {
         Ok(res) => println!("sent {}", res.status()),
         Err(err) => eprintln!("err: {err}",),
diff --git a/src/lib.rs b/src/lib.rs
index da1504c..b07b316 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -21,9 +21,9 @@
 //! # Features
 //! The projects has the following feature flags:
 //! * `rustls`: this feature flag switches the default SSL provider in the operating system (usually
-//! OpenSSL) with RusTLS, which is a TLS implementation in Rust.
+//!   OpenSSL) with RusTLS, which is a TLS implementation in Rust.
 //! * `native-tls`: enabled by default, this feature flag enabled the default SSL provider in the
-//! operating system (usually OpenSSL).
+//!   operating system (usually OpenSSL).
 //! * `blocking`: this feature flag allows you to construct a synchronous `SGClient`.
 //!
 //! ## Build Dependencies
diff --git a/src/v3.rs b/src/v3.rs
index 14a9d2a..016c489 100644
--- a/src/v3.rs
+++ b/src/v3.rs
@@ -8,12 +8,11 @@ use reqwest::header::{self, HeaderMap, HeaderValue, InvalidHeaderValue};
 use serde::Serialize;
 use serde_json::{to_value, value::Value, value::Value::Object, Map};
 
+use crate::error::{RequestNotSuccessful, SendgridError, SendgridResult};
 #[cfg(feature = "blocking")]
 use reqwest::blocking::Response as BlockingResponse;
 use reqwest::{Client, Response};
 
-use crate::error::{RequestNotSuccessful, SendgridError, SendgridResult};
-
 const V3_API_URL: &str = "https://api.sendgrid.com/v3/mail/send";
 
 /// Just a redefinition of a map to store string keys and values.
@@ -201,16 +200,31 @@ pub struct ASM {
 
 impl Sender {
     /// Construct a new V3 message sender.
-    pub fn new(api_key: String) -> Sender {
+    pub fn new(api_key: String, client: Option<Client>) -> Sender {
         Sender {
             api_key,
-            client: Client::new(),
+            client: client.unwrap_or_default(),
             #[cfg(feature = "blocking")]
             blocking_client: reqwest::blocking::Client::new(),
             host: V3_API_URL.to_string(),
         }
     }
 
+    /// Construct a new V3 message sender with a blocking client.
+    #[cfg(feature = "blocking")]
+    pub fn new_blocking(
+        api_key: String,
+        blocking_client: Option<reqwest::blocking::Client>,
+    ) -> Sender {
+        Sender {
+            api_key,
+            client: Client::new(),
+            #[cfg(feature = "blocking")]
+            blocking_client: blocking_client.unwrap_or_default(),
+            host: V3_API_URL.to_string(),
+        }
+    }
+
     /// Sets the host to use for the API. This is useful if you are using a proxy or a local
     /// development server. It should be a full URL, including the protocol.
     pub fn set_host<S: Into<String>>(&mut self, host: S) {