SMTP_HELO returns timeout when running email address validation-CodePudding

Using library py3-validate-email-1.0.5 (more here) to check if email address is valid, including SMTP check, I wasn't able to make it through check_smtp step, because I get following error:

Python script

from validate_email import validate_email
from validate_email import validate_email_or_fail
from csv import DictReader

# iterate over each line by column name
with open('email-list.csv', 'r') as read_obj:
    csv_dict_reader = DictReader(read_obj, delimiter=';')
    for row in csv_dict_reader:
        i = 1
        while i < 21:
            header_name = 'Email' str(i)
            if validate_email_or_fail(
                email_address=row[header_name],
                check_format=True,
                check_blacklist=True,
                check_dns=True,
                dns_timeout=10,
                check_smtp=True,
                smtp_timeout=5,
                smtp_helo_host='emailsrv.domain.com',
                smtp_from_address='[email protected]',
                smtp_skip_tls=False,
                smtp_tls_context=None,
                smtp_debug=False):
                print('Email '   row[header_name]   ' is valid.')
            else:
                print('Email '   row[header_name]   ' is invalid.')
            i  = 1

Error:

Traceback (most recent call last):
  File "//./main.py", line 13, in <module>
    if validate_email_or_fail(
  File "/usr/local/lib/python3.9/site-packages/validate_email/validate_email.py", line 59, in validate_email_or_fail
    return smtp_check(
  File "/usr/local/lib/python3.9/site-packages/validate_email/smtp_check.py", line 229, in smtp_check
    return smtp_checker.check(hosts=mx_records)
  File "/usr/local/lib/python3.9/site-packages/validate_email/smtp_check.py", line 197, in check
    raise SMTPTemporaryError(error_messages=self.__temporary_errors)
validate_email.exceptions.SMTPTemporaryError: Temporary error in email address verification:
mx.server.com: 451 timed out (in reply to 'connect')

I figured there is problem with my DNS settings (probably), so I dockerized the script and run it on AWS EC2, where I have used elastic IP, attached it to the EC2 instance where docker container is running, I also setup reverse DNS for domain emailsrv.domain.com with this elastic IP. Tried to run the script, no change.

Then I added MX record pointing to the emailsrv.domain.com, but still no change. The DNS records are setup properly, because I have checked it with multiple DNS tools available.

Since the library doesn't require to actually use my email address login details, I wonder what can be the problem? Just to be sure, the email address used in the script doesn't exist, since I don't have smtp server setup on that instance, obviously.

Any ideas?

CodePudding user response：

Reason behind this was closed port on AWS EC2 instance. Opening the port in security group is not enough, you must send a request to AWS so they remove the restriction on port 25.

When they did that, works flawlessly.