Add option to set name during HELO in email settings

Cargo.lock

@@ -837,6 +837,17 @@ dependencies = [
  "digest 0.8.1",
 ]
 
+[[package]]
+name = "hostname"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c731c3e10504cc8ed35cfe2f1db4c9274c3d35fa486e3b31df46f068ef3e867"
+dependencies = [
+ "libc",
+ "match_cfg",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "html5ever"
 version = "0.22.5"
@@ -1095,6 +1106,7 @@ checksum = "deaf9b74d40fcb52d0f762eb08e45d5152b4db59d29bb73edd4cac7fe796862c"
 dependencies = [
  "base64 0.12.3",
  "bufstream",
+ "hostname",
  "hyperx",
  "idna 0.2.0",
  "line-wrap",
@@ -1214,6 +1226,12 @@ dependencies = [
  "tendril",
 ]
 
+[[package]]
+name = "match_cfg"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffbee8634e0d45d258acb448e7eaab3fce7a0a467395d4d9f228e3c1f01fb2e4"
+
 [[package]]
 name = "matches"
 version = "0.1.8"

Cargo.toml

@@ -92,7 +92,7 @@ num-traits = "0.2.12"
 num-derive = "0.3.0"
 
 # Email libraries
-lettre = { version = "0.10.0-alpha.1", features = ["smtp-transport", "builder", "serde", "native-tls"], default-features = false }
+lettre = { version = "0.10.0-alpha.1", features = ["smtp-transport", "builder", "serde", "native-tls", "hostname"], default-features = false }
 native-tls = "0.2.4"
 
 # Template library

src/config.rs

@@ -394,7 +394,9 @@ make_config! {
         /// Json form auth mechanism |> Defaults for ssl is "Plain" and "Login" and nothing for non-ssl connections. Possible values: ["Plain", "Login", "Xoauth2"]
         smtp_auth_mechanism:    String, true,   option;
         /// SMTP connection timeout |> Number of seconds when to stop trying to connect to the SMTP server
-        smtp_timeout:           u64,     true,   def,     15;
+        smtp_timeout:           u64,    true,   def,     15;
+        /// Server name sent during HELO |> By default this value should be is on the machine's hostname, but might need to be changed in case it trips some anti-spam filters
+        helo_name:              String, true,   option;
     },
 
     /// Email 2FA Settings

src/mail.rs

@@ -2,6 +2,7 @@ use std::str::FromStr;
 
 use lettre::message::{header, Mailbox, Message, MultiPart, SinglePart};
 use lettre::transport::smtp::authentication::{Credentials, Mechanism as SmtpAuthMechanism};
+use lettre::transport::smtp::extension::ClientId;
 use lettre::{Address, SmtpTransport, Tls, TlsParameters, Transport};
 
 use native_tls::{Protocol, TlsConnector};
@@ -42,6 +43,11 @@ fn mailer() -> SmtpTransport {
         _ => smtp_client,
     };
 
+    let smtp_client = match CONFIG.helo_name() {
+        Some(helo_name) => smtp_client.hello_name(ClientId::new(helo_name)),
+        None => smtp_client,
+    };
+
     let smtp_client = match CONFIG.smtp_auth_mechanism() {
         Some(mechanism) => {
             let correct_mechanism = format!("\"{}\"", crate::util::upcase_first(mechanism.trim_matches('"')));