e79910431f
Reject email addresses that known to be undeliverable during signup. Some users signup with invalid email addresses, which causes the welcome email (which contains the email confirmation link) to bounce. Too many bounces hurt our ability to send mail. We check that an email address is undeliverable by checking if the domain has a mail server and if the server returns an invalid address error when attempting to send mail. This isn't foolproof since some servers don't return an error if the address doesn't exist. If the checks fail we know the address is bad, but if the checks pass that doesn't guarantee the address is good. However, this is still good enough to filter out bad addresses for popular providers like Gmail and Microsoft that do return nonexistent address errors. The address existence check requires being able to connect to mail servers over port 25. This may fail if your network blocks port 25, which many home ISPs and hosting providers do by default.
116 lines
3.4 KiB
Ruby
116 lines
3.4 KiB
Ruby
require 'resolv'
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module EmailValidator
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module_function
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IGNORE_DOTS = %w[gmail.com]
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IGNORE_PLUS_ADDRESSING = %w[gmail.com hotmail.com outlook.com live.com]
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IGNORE_MINUS_ADDRESSING = %w[yahoo.com]
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CANONICAL_DOMAINS = {
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"googlemail.com" => "gmail.com",
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"hotmail.co.uk" => "outlook.com",
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"hotmail.co.jp" => "outlook.com",
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"hotmail.co.th" => "outlook.com",
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"hotmail.com" => "outlook.com",
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"hotmail.ca" => "outlook.com",
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"hotmail.de" => "outlook.com",
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"hotmail.es" => "outlook.com",
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"hotmail.fr" => "outlook.com",
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"hotmail.it" => "outlook.com",
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"live.com.au" => "outlook.com",
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"live.com.ar" => "outlook.com",
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"live.com.mx" => "outlook.com",
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"live.co.uk" => "outlook.com",
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"live.com" => "outlook.com",
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"live.ca" => "outlook.com",
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"live.cl" => "outlook.com",
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"live.cn" => "outlook.com",
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"live.de" => "outlook.com",
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"live.fr" => "outlook.com",
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"live.it" => "outlook.com",
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"live.jp" => "outlook.com",
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"live.nl" => "outlook.com",
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"live.se" => "outlook.com",
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"msn.com" => "outlook.com",
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"yahoo.com.au" => "yahoo.com",
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"yahoo.com.ar" => "yahoo.com",
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"yahoo.com.br" => "yahoo.com",
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"yahoo.com.cn" => "yahoo.com",
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"yahoo.com.hk" => "yahoo.com",
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"yahoo.com.mx" => "yahoo.com",
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"yahoo.com.ph" => "yahoo.com",
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"yahoo.com.sg" => "yahoo.com",
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"yahoo.com.tw" => "yahoo.com",
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"yahoo.com.vn" => "yahoo.com",
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"yahoo.co.id" => "yahoo.com",
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"yahoo.co.kr" => "yahoo.com",
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"yahoo.co.jp" => "yahoo.com",
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"yahoo.co.uk" => "yahoo.com",
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"yahoo.ca" => "yahoo.com",
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"yahoo.cn" => "yahoo.com",
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"yahoo.de" => "yahoo.com",
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"yahoo.es" => "yahoo.com",
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"yahoo.fr" => "yahoo.com",
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"yahoo.it" => "yahoo.com",
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"ymail.com" => "yahoo.com",
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"126.com" => "163.com",
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"aim.com" => "aol.com",
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"gmx.com" => "gmx.net",
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"gmx.at" => "gmx.net",
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"gmx.ch" => "gmx.net",
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"gmx.de" => "gmx.net",
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"gmx.fr" => "gmx.net",
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"gmx.us" => "gmx.net",
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}
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def normalize(address)
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return nil unless address.count("@") == 1
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name, domain = address.downcase.split("@")
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domain = CANONICAL_DOMAINS.fetch(domain, domain)
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name = name.delete(".") if domain.in?(IGNORE_DOTS)
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name = name.gsub(/\+.*\z/, "") if domain.in?(IGNORE_PLUS_ADDRESSING)
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name = name.gsub(/-.*\z/, "") if domain.in?(IGNORE_MINUS_ADDRESSING)
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"#{name}@#{domain}"
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end
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def undeliverable?(to_address, from_address: Danbooru.config.contact_email, timeout: 3)
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mail_server = mx_domain(to_address, timeout: timeout)
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mail_server.nil? || rcpt_to_failed?(to_address, from_address, mail_server, timeout: timeout)
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rescue
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false
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end
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def rcpt_to_failed?(to_address, from_address, mail_server, timeout: nil)
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return false unless smtp_enabled?
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from_domain = Mail::Address.new(from_address).domain
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smtp = Net::SMTP.new(mail_server)
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smtp.read_timeout = timeout
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smtp.open_timeout = timeout
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smtp.start(from_domain) do |conn|
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conn.mailfrom(from_address)
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# Net::SMTPFatalError is raised if RCPT TO returns a 5xx error.
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response = conn.rcptto(to_address) rescue $!
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return response.is_a?(Net::SMTPFatalError)
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end
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end
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def mx_domain(to_address, timeout: nil)
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domain = Mail::Address.new(to_address).domain
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dns = Resolv::DNS.new
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dns.timeouts = timeout
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response = dns.getresource(domain, Resolv::DNS::Resource::IN::MX)
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response.exchange.to_s
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rescue Resolv::ResolvError
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nil
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end
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end
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