feat(email): Add SMTP support to allow mails through self hosted/cust…

…om SMTP server (#6617)

Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>

config/development.toml

@@ -311,7 +311,7 @@ wildcard_origin = true
 sender_email = "[email protected]"
 aws_region = ""
 allowed_unverified_days = 1
-active_email_client = "SES"
+active_email_client = "NO_EMAIL_CLIENT"
 recon_recipient_email = "[email protected]"
 prod_intent_recipient_email = "[email protected]"
 

config/docker_compose.toml

@@ -676,7 +676,7 @@ connector_list = "cybersource"
 sender_email = "[email protected]"                 # Sender email
 aws_region = ""                                      # AWS region used by AWS SES
 allowed_unverified_days = 1                          # Number of days the api calls ( with jwt token ) can be made without verifying the email
-active_email_client = "SES"                          # The currently active email client
+active_email_client = "NO_EMAIL_CLIENT"              # The currently active email client
 recon_recipient_email = "[email protected]"          # Recipient email for recon request email
 prod_intent_recipient_email = "[email protected]" # Recipient email for prod intent email
 

crates/external_services/Cargo.toml

@@ -29,6 +29,7 @@ error-stack = "0.4.1"
 hex = "0.4.3"
 hyper = "0.14.28"
 hyper-proxy = "0.9.1"
+lettre = "0.11.10"
 once_cell = "1.19.0"
 serde = { version = "1.0.197", features = ["derive"] }
 thiserror = "1.0.58"

crates/external_services/src/email.rs

@@ -7,6 +7,12 @@ use serde::Deserialize;
 /// Implementation of aws ses client
 pub mod ses;
 
+/// Implementation of SMTP server client
+pub mod smtp;
+
+/// Implementation of Email client when email support is disabled
+pub mod no_email;
+
 /// Custom Result type alias for Email operations.
 pub type EmailResult<T> = CustomResult<T, EmailError>;
 
@@ -114,14 +120,27 @@ dyn_clone::clone_trait_object!(EmailClient<RichText = Body>);
 
 /// List of available email clients to choose from
 #[derive(Debug, Clone, Default, Deserialize)]
-pub enum AvailableEmailClients {
+#[serde(tag = "active_email_client")]
+#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
+pub enum EmailClientConfigs {
     #[default]
+    /// Default Email client to use when no client is specified
+    NoEmailClient,
     /// AWS ses email client
-    SES,
+    Ses {
+        /// AWS SES client configuration
+        aws_ses: ses::SESConfig,
+    },
+    /// Other Simple SMTP server
+    Smtp {
+        /// SMTP server configuration
+        smtp: smtp::SmtpServerConfig,
+    },
 }
 
 /// Struct that contains the settings required to construct an EmailClient.
 #[derive(Debug, Clone, Default, Deserialize)]
+#[serde(default)]
 pub struct EmailSettings {
     /// The AWS region to send SES requests to.
     pub aws_region: String,
@@ -132,11 +151,9 @@ pub struct EmailSettings {
     /// Sender email
     pub sender_email: String,
 
-    /// Configs related to AWS Simple Email Service
-    pub aws_ses: Option<ses::SESConfig>,
-
-    /// The active email client to use
-    pub active_email_client: AvailableEmailClients,
+    #[serde(flatten)]
+    /// The client specific configurations
+    pub client_config: EmailClientConfigs,
 
     /// Recipient email for recon emails
     pub recon_recipient_email: pii::Email,
@@ -145,6 +162,17 @@ pub struct EmailSettings {
     pub prod_intent_recipient_email: pii::Email,
 }
 
+impl EmailSettings {
+    /// Validation for the Email client specific configurations
+    pub fn validate(&self) -> Result<(), &'static str> {
+        match &self.client_config {
+            EmailClientConfigs::Ses { ref aws_ses } => aws_ses.validate(),
+            EmailClientConfigs::Smtp { ref smtp } => smtp.validate(),
+            EmailClientConfigs::NoEmailClient => Ok(()),
+        }
+    }
+}
+
 /// Errors that could occur from EmailClient.
 #[derive(Debug, thiserror::Error)]
 pub enum EmailError {

crates/external_services/src/email/no_email.rs

@@ -0,0 +1,37 @@
+use common_utils::{errors::CustomResult, pii};
+use router_env::logger;
+
+use crate::email::{EmailClient, EmailError, EmailResult, IntermediateString};
+
+/// Client when email support is disabled
+#[derive(Debug, Clone, Default, serde::Deserialize)]
+pub struct NoEmailClient {}
+
+impl NoEmailClient {
+    /// Constructs a new client when email is disabled
+    pub async fn create() -> Self {
+        Self {}
+    }
+}
+
+#[async_trait::async_trait]
+impl EmailClient for NoEmailClient {
+    type RichText = String;
+    fn convert_to_rich_text(
+        &self,
+        intermediate_string: IntermediateString,
+    ) -> CustomResult<Self::RichText, EmailError> {
+        Ok(intermediate_string.into_inner())
+    }
+
+    async fn send_email(
+        &self,
+        _recipient: pii::Email,
+        _subject: String,
+        _body: Self::RichText,
+        _proxy_url: Option<&String>,
+    ) -> EmailResult<()> {
+        logger::info!("Email not sent as email support is disabled, please enable any of the supported email clients to send emails");
+        Ok(())
+    }
+}

crates/external_services/src/email/ses.rs

@@ -7,7 +7,7 @@ use aws_sdk_sesv2::{
     Client,
 };
 use aws_sdk_sts::config::Credentials;
-use common_utils::{errors::CustomResult, ext_traits::OptionExt, pii};
+use common_utils::{errors::CustomResult, pii};
 use error_stack::{report, ResultExt};
 use hyper::Uri;
 use masking::PeekInterface;
@@ -19,6 +19,7 @@ use crate::email::{EmailClient, EmailError, EmailResult, EmailSettings, Intermed
 #[derive(Debug, Clone)]
 pub struct AwsSes {
     sender: String,
+    ses_config: SESConfig,
     settings: EmailSettings,
 }
 
@@ -32,6 +33,21 @@ pub struct SESConfig {
     pub sts_role_session_name: String,
 }
 
+impl SESConfig {
+    /// Validation for the SES client specific configs
+    pub fn validate(&self) -> Result<(), &'static str> {
+        use common_utils::{ext_traits::ConfigExt, fp_utils::when};
+
+        when(self.email_role_arn.is_default_or_empty(), || {
+            Err("email.aws_ses.email_role_arn must not be empty")
+        })?;
+
+        when(self.sts_role_session_name.is_default_or_empty(), || {
+            Err("email.aws_ses.sts_role_session_name must not be empty")
+        })
+    }
+}
+
 /// Errors that could occur during SES operations.
 #[derive(Debug, thiserror::Error)]
 pub enum AwsSesError {
@@ -67,35 +83,34 @@ pub enum AwsSesError {
 
 impl AwsSes {
     /// Constructs a new AwsSes client
-    pub async fn create(conf: &EmailSettings, proxy_url: Option<impl AsRef<str>>) -> Self {
+    pub async fn create(
+        conf: &EmailSettings,
+        ses_config: &SESConfig,
+        proxy_url: Option<impl AsRef<str>>,
+    ) -> Self {
         // Build the client initially which will help us know if the email configuration is correct
-        Self::create_client(conf, proxy_url)
+        Self::create_client(conf, ses_config, proxy_url)
             .await
             .map_err(|error| logger::error!(?error, "Failed to initialize SES Client"))
             .ok();
 
         Self {
             sender: conf.sender_email.clone(),
+            ses_config: ses_config.clone(),
             settings: conf.clone(),
         }
     }
 
     /// A helper function to create ses client
     pub async fn create_client(
         conf: &EmailSettings,
+        ses_config: &SESConfig,
         proxy_url: Option<impl AsRef<str>>,
     ) -> CustomResult<Client, AwsSesError> {
         let sts_config = Self::get_shared_config(conf.aws_region.to_owned(), proxy_url.as_ref())?
             .load()
             .await;
 
-        let ses_config = conf
-            .aws_ses
-            .as_ref()
-            .get_required_value("aws ses configuration")
-            .attach_printable("The selected email client is aws ses, but configuration is missing")
-            .change_context(AwsSesError::MissingConfigurationVariable("aws_ses"))?;
-
         let role = aws_sdk_sts::Client::new(&sts_config)
             .assume_role()
             .role_arn(&ses_config.email_role_arn)
@@ -219,7 +234,7 @@ impl EmailClient for AwsSes {
     ) -> EmailResult<()> {
         // Not using the same email client which was created at startup as the role session would expire
         // Create a client every time when the email is being sent
-        let email_client = Self::create_client(&self.settings, proxy_url)
+        let email_client = Self::create_client(&self.settings, &self.ses_config, proxy_url)
             .await
             .change_context(EmailError::ClientBuildingFailure)?;