They can get ridiculously convoluted as in the case above and, according to the specification, are often too strict anyway.

validating email addresses using regular expressions-59validating email addresses using regular expressions-47

Validating email addresses using regular expressions video

In fact, you already would need to add the extension.4.

Way complicated approach A Perl module has a long regular expression based on the standard description of an email address.

Here’s a fairly common code sample from Rails Applications with some sort of authentication system: If you’re experienced at Regex, this seems simple. Sections 3.2.4 and 3.4.1 of the RFC go into the requirements on how an email address needs to be formatted and, well, there’s not much you can’t do in your email address when quotes or backslashes are involved.

If (like me when I first saw this) you AREN’T experienced at Regex, it takes a while to parse. The local string (the part of the email address that comes before the @) can contain any of these characters: is a valid email address. For this reason, for a time I began running any email address against the following regular expression instead: Simple, right? This is often the most I do and, when paired with a confirmation field for the email address on your registration form, can alleviate most problems with user error.

This has NOTHING to do with whether a particular string corresponds to a mailbox known by a mail server, nor whether said server is permitted to actually deposit email into an existing box, etc.

None of that can be determined by regular expression - or for that matter, by much of anything other than a mail delivery program!

Downside: It still allows many invalid email addresses, and misses some longer domain extensions (.museum, for example).3. Meet in the middle approach You'll have to decide, if you haven't already, which regular expression to use.

Specify all the domain extensions approach Reddit user teye points to his regex, which only allows domain extensions that actually exist:([a-z0-9][-a-z0-9_\ \.]*[a-z0-9])@([a-z0-9][-a-z0-9\.]*[a-z0-9]\.(arpa|root|aero|biz|cat|com|coop|edu|gov|info|int|jobs|mil|mobi|museum|name|net|org|pro|tel|travel|ac|ad|ae|af|ag|ai|al|am|an|ao|aq|ar|as|at|au|aw|ax|az|ba|bb|bd|be|bf|bg|bh|bi|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|cr|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|ee|eg|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gg|gh|gi|gl|gm|gn|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|im|in|io|iq|ir|is|it|je|jm|jo|jp|ke|kg|kh|ki|km|kn|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|mg|mh|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|mv|mw|mx|my|mz|na|nc|ne|nf|ng|ni|nl|no|np|nr|nu|nz|om|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|ps|pt|pw|py|qa|re|ro|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sy|sz|tc|td|tf|tg|th|tj|tk|tl|tm|tn|to|tp|tr|tt|tv|tw|tz|ua|ug|uk|um|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|yu|za|zm|zw)|([0-9]\.[0-9]))Upside: It doesn't allow [email protected]! You'd have to update any time new domain extensions are announced. Likely, you'll choose somewhere in the middle of the examples we've given. Info has a good run-down of the trade-offs of different approaches.

But mime::parseaddress fails (LV By fail, do you mean does not perform functions it is defined to do - or does it mean does not perform functions that you want it to do?

The documentation for the function states that if more than one address is provided, they will be seperated by commas!

The regular expression pattern is interpreted as follows. Regular Expressions Public Class Regex Utilities Public Shared Function Is Valid Email(email As String) As Boolean If String. methods can be included in a library of regular expression utility methods, or they can be included as private static or instance methods in the application class. Compile To Assembly method to include this regular expression in a regular expression library.