Zend_Validate_EmailAddress allows you to validate an email address. The validator first splits the email address on local-part @ hostname and attempts to match these against known specifications for email addresses and hostnames. A basic example of usage is below: isValid($email)) { // email appears to be valid } else { // email is invalid; print the reasons foreach ($validator->getMessages() as $message) { echo "$message\n"; } } ]]> This will match the email address $email and on failure populate getMessages() with useful error messages. Zend_Validate_EmailAddress supports several options which can either be set at initiation, by giving an array with the related options, or afterwards, by using setOptions(). The following options are supported: allow: Defines which type of domain names are accepted. This option is used in conjunction with the hostname option to set the hostname validator. For more informations about possible values of this option, look at Hostname and possible ALLOW* constants. This option defaults to ALLOW_DNS. deep: Defines if the servers MX records should be verified by a deep check. When this option is set to TRUE then additionally to MX records also the A, A6 and AAAA records are used to verify if the server accepts emails. This option defaults to FALSE. domain: Defines if the domain part should be checked. When this option is set to FALSE, then only the local part of the email address will be checked. In this case the hostname validator will not be called. This option defaults to TRUE. hostname: Sets the hostname validator with which the domain part of the email address will be validated. mx: Defines if the MX records from the server should be detected. If this option is defined to TRUE then the MX records are used to verify if the server accepts emails. This option defaults to FALSE. setOptions(array('domain' => false)); ]]> Zend_Validate_EmailAddress will match any valid email address according to RFC2822. For example, valid emails include bob@domain.com, bob+jones@domain.us, "bob@jones"@domain.com and "bob jones"@domain.com. Some obsolete email formats will not currently validate (e.g. carriage returns or a "\" character in an email address). If you need Zend_Validate_EmailAddress to check only the local part of an email address, and want to disable validation of the hostname, you can set the domain option to FALSE. This forces Zend_Validate_EmailAddress not to validate the hostname part of the email address. setOptions(array('domain' => FALSE)); ]]> The hostname part of an email address is validated against Zend_Validate_Hostname. By default only DNS hostnames of the form domain.com are accepted, though if you wish you can accept IP addresses and Local hostnames too. To do this you need to instantiate Zend_Validate_EmailAddress passing a parameter to indicate the type of hostnames you want to accept. More details are included in Zend_Validate_Hostname, though an example of how to accept both DNS and Local hostnames appears below: isValid($email)) { // email appears to be valid } else { // email is invalid; print the reasons foreach ($validator->getMessages() as $message) { echo "$message\n"; } } ]]> Just because an email address is in the correct format, it doesn't necessarily mean that email address actually exists. To help solve this problem, you can use MX validation to check whether an MX (email) entry exists in the DNS record for the email's hostname. This tells you that the hostname accepts email, but doesn't tell you the exact email address itself is valid. MX checking is not enabled by default. To enable MX checking you can pass a second parameter to the Zend_Validate_EmailAddress constructor. Zend_Validate_Hostname::ALLOW_DNS, 'mx' => true ) ); ]]> Within Windows environments MX checking is only available when PHP 5.3 or above is used. Below PHP 5.3 MX checking will not be used even if it's activated within the options. Alternatively you can either pass TRUE or FALSE to setValidateMx() to enable or disable MX validation. By enabling this setting network functions will be used to check for the presence of an MX record on the hostname of the email address you wish to validate. Please be aware this will likely slow your script down. Sometimes validation for MX records returns FALSE, even if emails are accepted. The reason behind this behaviour is, that servers can accept emails even if they do not provide a MX record. In this case they can provide A, A6 or AAAA records. To allow Zend_Validate_EmailAddress to check also for these other records, you need to set deep MX validation. This can be done at initiation by setting the deep option or by using setOptions(). Zend_Validate_Hostname::ALLOW_DNS, 'mx' => true, 'deep' => true ) ); ]]> You should be aware that enabling MX check will slow down you script because of the used network functions. Enabling deep check will slow down your script even more as it searches the given server for 3 additional types. You should note that MX validation is only accepted for external servers. When deep MX validation is enabled, then local IP addresses like 192.168.* or 169.254.* are not accepted. Zend_Validate_EmailAddress will also match international characters that exist in some domains. This is known as International Domain Name (IDN) support. This is enabled by default, though you can disable this by changing the setting via the internal Zend_Validate_Hostname object that exists within Zend_Validate_EmailAddress. getHostnameValidator()->setValidateIdn(false); ]]> More information on the usage of setValidateIdn() appears in the Zend_Validate_Hostname documentation. Please note IDNs are only validated if you allow DNS hostnames to be validated. By default a hostname will be checked against a list of known TLDs. This is enabled by default, though you can disable this by changing the setting via the internal Zend_Validate_Hostname object that exists within Zend_Validate_EmailAddress. getHostnameValidator()->setValidateTld(false); ]]> More information on the usage of setValidateTld() appears in the Zend_Validate_Hostname documentation. Please note TLDs are only validated if you allow DNS hostnames to be validated. Zend_Validate_EmailAddress makes also use of Zend_Validate_Hostname to check the hostname part of a given email address. As with Zend Framework 1.10 you can simply set messages for Zend_Validate_Hostname from within Zend_Validate_EmailAddress. setMessages( array( Zend_Validate_Hostname::UNKNOWN_TLD => "I don't know the TLD you gave" ) ); ]]> Before Zend Framework 1.10 you had to attach the messages to your own Zend_Validate_Hostname, and then set this validator within Zend_Validate_EmailAddress to get your own messages returned.