Validate email address on user input

pokoli · August 18, 2022, 3:11pm

We found several users that have problem with notification emails due to wrong input of the party emails. As we have a validation for phone numbers I’m wonder if we should not have some for email also.

If found there is an email-validation library on PyPi that may do the job for us. I see it checks also the correctnes of DNS records and that is something that we may want to disable on systems without network access.

Like with phone numbers this library will be optional (but enabled by default on our docker image) so anyone that does not want to have the email validation can just skip the instalation of the library.

Toughts?

ced · August 18, 2022, 3:30pm

email validation is difficult but this library does not look bad.
For the DNS validation I think in case of timeout we should allow the user to skip it via a warning.
Also test_environment should be set when running tests.

nicoe · August 18, 2022, 3:41pm

It’s a bit a pity that it’s a parameter to the actual validation call:

github.com

JoshData/python-email-validator/blob/main/email_validator/init.py#L266


      
          # Export the main method, helper methods, and the public data types.
          from .exceptions_types import ValidatedEmail, EmailNotValidError, \
                                        EmailSyntaxError, EmailUndeliverableError
          from .validate_email import validate_email
          from .version import __version__
          
          __all__ = ["validate_email",
                     "ValidatedEmail", "EmailNotValidError",
                     "EmailSyntaxError", "EmailUndeliverableError",
                     "caching_resolver", "__version__"]
          
          
          def caching_resolver(*args, **kwargs):
              # Lazy load `deliverability` as it is slow to import (due to dns.resolver)
              from .deliverability import caching_resolver
          
              return caching_resolver(*args, **kwargs)
          
          
          # These global attributes are a part of the library's API and can be
          # changed by library users.
          
          # Default values for keyword arguments.
          
          ALLOW_SMTPUTF8 = True
          ALLOW_QUOTED_LOCAL = False
          ALLOW_DOMAIN_LITERAL = False
          GLOBALLY_DELIVERABLE = True
          CHECK_DELIVERABILITY = True
          TEST_ENVIRONMENT = False
          DEFAULT_TIMEOUT = 15  # secs
          
          # IANA Special Use Domain Names
          # Last Updated 2021-09-21
          # https://www.iana.org/assignments/special-use-domain-names/special-use-domain-names.txt
          #
          # The domain names without dots would be caught by the check that the domain
          # name in an email address must have a period, but this list will also catch
          # subdomains of these domains, which are also reserved.
          SPECIAL_USE_DOMAIN_NAMES = [
              # The "arpa" entry here is consolidated from a lot of arpa subdomains
              # for private address (i.e. non-routable IP addresses like 172.16.x.x)
              # reverse mapping, plus some other subdomains. Although RFC 6761 says
              # that application software should not treat these domains as special,
              # they are private-use domains and so cannot have globally deliverable
              # email addresses, which is an assumption of this library, and probably
              # all of arpa is similarly special-use, so we reject it all.
              "arpa",
          
              # RFC 6761 says applications "SHOULD NOT" treat the "example" domains
              # as special, i.e. applications should accept these domains.
              #
              # The domain "example" alone fails our syntax validation because it
              # lacks a dot (we assume no one has an email address on a TLD directly).
              # "@example.com/net/org" will currently fail DNS-based deliverability
              # checks because IANA publishes a NULL MX for these domains, and
              # "@mail.example[.com/net/org]" and other subdomains will fail DNS-
              # based deliverability checks because IANA does not publish MX or A
              # DNS records for these subdomains.
              # "example", # i.e. "wwww.example"
              # "example.com",
              # "example.net",
              # "example.org",
          
              # RFC 6761 says that applications are permitted to treat this domain
              # as special and that DNS should return an immediate negative response,
              # so we also immediately reject this domain, which also follows the
              # purpose of the domain.
              "invalid",
          
              # RFC 6762 says that applications "may" treat ".local" as special and
              # that "name resolution APIs and libraries SHOULD recognize these names
              # as special," and since ".local" has no global definition, we reject
              # it, as we expect email addresses to be gloally routable.
              "local",
          
              # RFC 6761 says that applications (like this library) are permitted
              # to treat "localhost" as special, and since it cannot have a globally
              # deliverable email address, we reject it.
              "localhost",
          
              # RFC 7686 says "applications that do not implement the Tor protocol
              # SHOULD generate an error upon the use of .onion and SHOULD NOT
              # perform a DNS lookup.
              "onion",
          
              # Although RFC 6761 says that application software should not treat
              # these domains as special, it also warns users that the address may
              # resolve differently in different systems, and therefore it cannot
              # have a globally routable email address, which is an assumption of
              # this library, so we reject "@test" and "@*.test" addresses, unless
              # the test_environment keyword argument is given, to allow their use
              # in application-level test environments. These domains will generally
              # fail deliverability checks because "test" is not an actual TLD.
              "test",
          ]

(and setting the module level variable won’t work since the default value is set before setting it of course ).

ced · August 18, 2022, 3:43pm

This can be done using Pool.test value.

ced · August 25, 2022, 10:34am

The formatting should also be applied to web.user because for now we are just lowering the full address (cf. _format_email).

ced · April 29, 2023, 5:16pm

Implemented in Validate email addresses (!494) · Merge requests · Tryton / Tryton · GitLab

vincent · September 18, 2023, 9:56am

Is this implemented only as a feature for developers?
I could not see how an administrator or user can use this feature.

ced · September 18, 2023, 10:18am

They fill an email address and the server raise or not en error.

Mayoxord · October 16, 2024, 1:37pm

Ensuring accurate email inputs can really streamline communication and reduce errors. Using a library like the one you mentioned from PyPi sounds like a solid approach, especially with its DNS record checking capability (even though you might need to tweak it for offline systems).

ced · October 17, 2024, 6:02am

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