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// check-if-email-exists // Copyright (C) 2018-2020 Amaury Martiny // This program is free software: you can redistribute it and/or modify // it under the terms of the GNU Affero General Public License as published // by the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Affero General Public License for more details. // You should have received a copy of the GNU Affero General Public License // along with this program. If not, see <https://www.gnu.org/licenses/>. //! `check-if-email-exists` lets you check if an email address exists without //! sending any email. //! //! Under the hood, it connects to the email address's SMTP server, and, //! analyzing the server's responses against some SMTP commands, finds out //! information about the email address, such as: //! - Email deliverability: Is an email sent to this address deliverable? //! - Syntax validation. Is the address syntactically valid? //! - DNS records validation. Does the domain of the email address have valid //! MX DNS records? //! - Disposable email address (DEA) validation. Is the address provided by a //! known disposable email address provider? //! - SMTP server validation. Can the mail exchanger of the email address //! domain be contacted successfully? //! - Mailbox disabled. Has this email address been disabled by the email //! provider? //! - Full inbox. Is the inbox of this mailbox full? //! - Catch-all address. Is this email address a catch-all address? //! //! ```rust //! use check_if_email_exists::{check_email, CheckEmailInput}; //! //! async fn check() { //! // Let's say we want to test the deliverability of someone@gmail.com. //! let mut input = CheckEmailInput::new(vec!["someone@gmail.com".into()]); //! //! // Optionally, we can also tweak the configuration parameters used in the //! // verification. //! input //! .from_email("me@example.org".into()) // Used in the `MAIL FROM:` command //! .hello_name("example.org".into()); // Used in the `EHLO` command //! //! // Verify this input, using async/await syntax. //! let result = check_email(&input).await; //! //! // `result` is a `Vec<CheckEmailOutput>`, where the CheckEmailOutput //! // struct contains all information about one email. //! println!("{:?}", result); //! } //! ``` pub mod misc; pub mod mx; pub mod smtp; pub mod syntax; mod util; use async_smtp::smtp::SMTP_PORT; use futures::future; use misc::{check_misc, MiscDetails}; use mx::check_mx; use smtp::{check_smtp, SmtpDetails, SmtpError}; use syntax::check_syntax; use util::constants::LOG_TARGET; pub use util::input_output::*; /// Given an email's misc and smtp details, calculate an estimate of our /// confidence on how reachable the email is. fn calculate_reachable(misc: &MiscDetails, smtp: &Result<SmtpDetails, SmtpError>) -> Reachable { if let Ok(smtp) = smtp { if misc.is_disposable || misc.is_role_account || smtp.is_catch_all || smtp.has_full_inbox { return Reachable::Risky; } if !smtp.is_deliverable || !smtp.can_connect_smtp || smtp.is_disabled { return Reachable::Invalid; } Reachable::Safe } else { Reachable::Unknown } } /// Check a single emails. This assumes this `input.check_email` contains /// exactly one element. If it contains more, elements other than the first /// one will be ignored. /// /// # Panics /// /// This function panics if `input.check_email` is empty. async fn check_single_email(input: CheckEmailInput) -> CheckEmailOutput { let to_email = &input.to_emails[0]; log::debug!(target: LOG_TARGET, "Checking email \"{}\"", to_email); let my_syntax = check_syntax(to_email.as_ref()); if !my_syntax.is_valid_syntax { return CheckEmailOutput { input: to_email.to_string(), is_reachable: Reachable::Invalid, syntax: my_syntax, ..Default::default() }; } log::debug!( target: LOG_TARGET, "Found the following syntax validation: {:?}", my_syntax ); let my_mx = match check_mx(&my_syntax).await { Ok(m) => m, e => { // This happens when there's an internal error while checking MX // records. Should happen fairly rarely. return CheckEmailOutput { input: to_email.to_string(), is_reachable: Reachable::Unknown, mx: e, syntax: my_syntax, ..Default::default() }; } }; log::debug!( target: LOG_TARGET, "Found the following MX hosts {:?}", my_mx ); // Return if we didn't find any MX records. if my_mx.lookup.is_err() { return CheckEmailOutput { input: to_email.to_string(), is_reachable: Reachable::Invalid, mx: Ok(my_mx), syntax: my_syntax, ..Default::default() }; } let my_misc = check_misc(&my_syntax); log::debug!( target: LOG_TARGET, "Found the following misc details: {:?}", my_misc ); // We simply take the first lookup result, and connect to that SMTP server. // FIXME Add retry mechanism to other lookup results. let my_smtp = my_mx .lookup .as_ref() .expect("If lookup is error, we already returned. qed.") .iter() .next() .map(|host| { check_smtp( my_syntax .address .as_ref() .expect("We already checked that the email has valid format. qed."), host.exchange(), // FIXME We could add ports 465 and 587 too. SMTP_PORT, my_syntax.domain.as_ref(), &input, ) }) .expect("Lookup cannot be empty. qed.") .await; CheckEmailOutput { input: to_email.to_string(), is_reachable: calculate_reachable(&my_misc, &my_smtp), misc: Ok(my_misc), mx: Ok(my_mx), smtp: my_smtp, syntax: my_syntax, } } /// The main function of this library: takes as input a list of email addresses /// to check. Then performs syntax, mx, smtp and misc checks, and outputs a /// list of results. pub async fn check_email(inputs: &CheckEmailInput) -> Vec<CheckEmailOutput> { // FIXME Obviously, the below `join_all` is not optimal. Some optimizations // include: // - if multiple email addresses share the same domain, we should only do // `check_mx` call for all these email addresses. // - if multiple email addresses share the same domain, we should call // `check_smtp` with grouped email addresses, to share a SMTP connection. // ref: https://github.com/amaurymartiny/check-if-email-exists/issues/65. let inputs = inputs.to_emails.iter().map(|email| { // Create n `CheckEmailInput`s, each with one email address. CheckEmailInput { to_emails: vec![email.clone()], from_email: inputs.from_email.clone(), hello_name: inputs.hello_name.clone(), proxy: inputs.proxy.clone(), smtp_timeout: inputs.smtp_timeout, yahoo_use_api: inputs.yahoo_use_api, } }); future::join_all(inputs.map(check_single_email)).await }