What is the best Java email address validation method?

Using the official java email package is the easiest:

public static boolean isValidEmailAddress(String email) {
   boolean result = true;
   try {
      InternetAddress emailAddr = new InternetAddress(email);
      emailAddr.validate();
   } catch (AddressException ex) {
      result = false;
   }
   return result;
}

Apache Commons validator can be used as mentioned in the other answers.

pom.xml:

<dependency>
    <groupId>commons-validator</groupId>
    <artifactId>commons-validator</artifactId>
    <version>1.4.1</version>
</dependency>

build.gradle:

compile 'commons-validator:commons-validator:1.4.1'

The import:

import org.apache.commons.validator.routines.EmailValidator;

The code:

String email = "[email protected]";
boolean valid = EmailValidator.getInstance().isValid(email);

and to allow local addresses

boolean allowLocal = true;
boolean valid = EmailValidator.getInstance(allowLocal).isValid(email);

Late answer, but I think it is simple and worthy:

    public boolean isValidEmailAddress(String email) {
           String ePattern = "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@((\\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\])|(([a-zA-Z\\-0-9]+\\.)+[a-zA-Z]{2,}))$";
           java.util.regex.Pattern p = java.util.regex.Pattern.compile(ePattern);
           java.util.regex.Matcher m = p.matcher(email);
           return m.matches();
    }

Test Cases:

For production purpose, Domain Name validations should be performed network-wise.

Apache Commons is generally known as a solid project. Keep in mind, though, you'll still have to send a verification email to the address if you want to ensure it's a real email, and that the owner wants it used on your site.

EDIT: There was a bug where it was too restrictive on domain, causing it to not accept valid emails from new TLDs.

This bug was resolved on 03/Jan/15 02:48 in commons-validator version 1.4.1