Amazing-Python-Scripts

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from dns import resolver
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import smtplib
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import socket
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import re
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# FIRST CHECK
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def check_syntax(email):
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    regex = r'^[a-z0-9]+[\._]?[a-z0-9]+[@]\w+[.]\w{2,3}$'
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    if (re.search(regex, email)):
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        print("Check 1 (Syntax) Passed")
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    else:
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        print("Check 1 FAILED! Bad Syntax, Invalid Email!")
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        exit()
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# SECOND CHECK
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def check_dns(email, domain):
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    try:
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        records = resolver.resolve(domain, 'MX')
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        mxRecord = str(records[0].exchange)
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        print("Check 2 (DNS -", mxRecord+") Passed")
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        return mxRecord
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    except:
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        print("Check 2 FAILED! The domain", domain,
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              "does not exist, Invalid Email!")
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        exit()
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# THIRD CHECK
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def check_response(email, domain, mxRecord):
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    try:
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        # Get local server hostname
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        host = socket.gethostname()
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        # SMTP lib setup (use debug level for full output)
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        server = smtplib.SMTP()
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        server.set_debuglevel(0)
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        # SMTP Conversation
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        server.connect(mxRecord)
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        server.helo(host)
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        server.mail(email)
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        code, message = server.rcpt(str(email))
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        server.quit()
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        # Assume 250 as Success
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        if code == 250:
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            print("Check 3 (SMTP response) Passed")
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            print(email, "is a VALID email address!")
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        else:
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            print("Check 3 FAILED! The user", email.split(
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                "@")[0], "does not exist, Invalid Email!")
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    except socket.error as socketerror:
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        print("Check 3 HALTED! The domain", domain,
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              ", either does not have an SMTP or have restricted access through external scripts")
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email = input("Enter your Email id :")
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domain = email.split("@")[-1]
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check_syntax(email)  # CHECK1
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mxRecord = check_dns(email, domain)  # CHECK2
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check_response(email, domain, mxRecord)  # CHECK3
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