id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
3138	isValidEmail accepts non-wellformed e-mail address. SMTP 'VRFY' and MX/A DNS lookup provides better validation.	mpjung@…	Adrian Holovaty	"Currently the E-Mail-Validator only checks for well formed e-mail addresses via a very simplified regular expression. This recently gave me troubles as an address with leading '-' was allowed. foo@-bar.de was validated correctly, but threw an error later when trying to send an e-mail using this address.

The Book “Mastering Regular Expressions” by Jeffrey E. F. Friedl comes with a very advanced regular expression (filling a complete A4 page if printed with a readable font) and quickly shows that the approach of a simple pattern match is not too great for validating e-mail addresses.

I have been looking at the SMTP RFC and found the command ""vrfy"" which allows the user to check if a specific e-mail address would be accepted as recipient. The python smtplib also supports this feature via the verify method so it would be quite easy to implement a validator that uses the default SMTP server to check for validness of entered e-mail addresses.

I would like to add a configuration variable called VALIDATE_EMAIL_ADDRESS_VIA_SMTP (better name?) which can be set to True if e-mail validation should be done via the configured SMTP host."	enhancement	closed	Validators		normal	wontfix	email validator smtp vrfy	mpjung@… mir@…	Design decision needed	0	0	0	0	0	0