fix!(core): Bump timeout to 45s, set retries to 1 (#1406)

BREAKING CHANGE: Vercel functions (used by https://app.reacher.email) usually timeout with a 504 error within less than 60s. So we should absolutely make a verification in less time than that.

After some testing, Reacher performs better with this setting:
- each SMTP connection times out after 45s, but we don't retry
over this previous setting
- each SMTP connection times out after ~20s, but we do retry once (to avoid greylisting in some rare cases)

Changing the default behaviour in this PR.

core/src/rules.json

@@ -8,7 +8,11 @@
 		"yahoo.fr": { "rules": ["SkipCatchAll"] }
 	},
 	"by_mx": {
-		"filter30.antispamcloud.com.": { "rules": ["HoneyPot"] }
+		"filter30.antispamcloud.com.": { "rules": ["HoneyPot"] },
+		"futuresinitiative.org.": { "rules": ["SmtpTimeout45s"] },
+		"mail.digimarcon.com.": { "rules": ["SmtpTimeout45s"] },
+		"mail.glasasoftball.org.": { "rules": ["SmtpTimeout45s"] },
+		"nosotrosorg.com.": { "rules": ["SmtpTimeout45s"] }
 	},
 	"by_mx_suffix": {
 		".antispamcloud.com.": {
@@ -19,7 +23,7 @@
 	"rules": {
 		"SkipCatchAll": { "_comment": "Don't perform catch-all check" },
 		"SmtpTimeout45s": {
-			"_comment": "Set SMTP connection timeout to at least 45s. If the user request set an even higher timeout, take that one. Please note that this timeout is **per SMTP connection**. By default, we try 2 connections per email: if the 1st one failed, then we connect again to avoid potential greylisting, in which case the whole verification takes 1min30s."
+			"_comment": "Set SMTP connection timeout to at least 45s. If the user request set an even higher timeout, take that one. Please note that this timeout is **per SMTP connection**. We might try 2 connections per email: if the 1st one failed, then we connect again to avoid potential greylisting, in which case the whole verification takes 1min30s."
 		}
 	}
 }

core/src/util/input_output.rs

@@ -182,7 +182,7 @@ pub struct CheckEmailInput {
 	/// Add timeout for the SMTP verification step. Set to None if you don't
 	/// want to use a timeout.
 	///
-	/// Defaults to 12s (more than 10s, but when run twice less than 30s).
+	/// Defaults to 30s.
 	pub smtp_timeout: Option<Duration>,
 	/// Select how to verify Yahoo emails.
 	///
@@ -203,9 +203,10 @@ pub struct CheckEmailInput {
 	/// Check if a the email address is present in HaveIBeenPwned API.
 	// If the api_key is filled, HaveIBeenPwned API is checked
 	pub haveibeenpwned_api_key: Option<String>,
-	/// Number of retries of SMTP connections to do.
+	/// Number of retries of SMTP connections to do. Setting to 2 might bypass
+	/// greylisting on some servers, but takes more time.
 	///
-	/// Defaults to 2 to avoid greylisting.
+	/// Defaults to 1.
 	pub retries: usize,
 	/// How to apply TLS to a SMTP client connection.
 	///
@@ -241,7 +242,7 @@ impl Default for CheckEmailInput {
 			proxy: None,
 			smtp_port: 25,
 			smtp_security: SmtpSecurity::default(),
-			smtp_timeout: Some(Duration::from_secs(12)),
+			smtp_timeout: Some(Duration::from_secs(45)),
 			#[cfg(not(feature = "headless"))]
 			yahoo_verif_method: YahooVerifMethod::Api,
 			#[cfg(feature = "headless")]
@@ -253,7 +254,7 @@ impl Default for CheckEmailInput {
 			hotmail_verif_method: HotmailVerifMethod::Headless,
 			check_gravatar: false,
 			haveibeenpwned_api_key: None,
-			retries: 2,
+			retries: 1,
 			skipped_domains: vec![],
 		}
 	}