Add mailersend client and improve EmailAddress behavior

Introduced a new email client, mailersend, and made improvements to the functionality of the EmailAddress type. Adjusted the test suite to match these changes and further updated some client traits and functions for better clarity and functionality.

- Added a client for the mailersend service, expanding the flexibility of the utility.
- Enhanced the functionality of the EmailAddress type, providing the ability to pass string literals directly. The change simplifies code and improves readability.
- Updated some client traits and functions for better clarity and expanded functionality.
- Test suite has been updated accordingly to reflect these changes.

Cargo.toml

@@ -45,6 +45,7 @@ mailersend = ["dep:reqwest"]
 
 [dev-dependencies]
 tokio-test = "0.4.4"
+wiremock = "0.6.0"
 
 [package.metadata.cargo-udeps.ignore]
 normal = ["log"]
@@ -55,4 +56,4 @@ development = ["tokio-test"]
 # document all features
 all-features = true
 # defines the configuration attribute `docsrs`
-rustdoc-args = ["--cfg", "docsrs"]
+rustdoc-args = ["--cfg", "docsrs"]

README.md

@@ -28,7 +28,7 @@ Based on the email client you want to support, you need to initialize email conf
 ```rust
 async fn send_email() {
     let email = EmailObject {
-        sender: "[email protected]".to_string(),
+        sender: "[email protected]",
         to: vec![EmailAddress { name: "Mail".to_string(), email: "[email protected]".to_string() }],
         subject: "subject".to_string(),
         plain: "plain body".to_string(),