Block certain email users / IPs from signing up with PHP explode

Often, we ask visitors to fill forms on our portals. As a measure to prevent ‘System Abuse’ from users with email accounts from free email providers, many forums and websites bar users with such mail IDs from signing-up for their services.

The following PHP script will do the same for your websites.

$emailadd = explode(“@”, $email);	//spilts string in ‘email’after ‘@’ and puts the result in ‘emailadd’
echo $emailadd[1];
$mailchk=”SELECT * FROM reposit WHERE email=’$emailadd’”; $answer=mysql_query($mailchk);	//this lines will check if ‘emailadd’ exists in the table ‘reposit’ of the database
$mcount=mysql_num_rows($answer);	//’mcount’ will have the number of rows in which the domain-name exists in ‘reposit’
if($mcount==1){ echo “You cannot use this mail account”; } else { whatever action you want }	//if an entry for the domain-name specified in ‘emailadd’ exists, the if-else is executed accordingly

Description of explode:

explode(separator, string, limit)

separator - Required. Specifies where to break the string

string – Required. The string to split

limit – Optional. Specifies the maximum number of array elements to return

Note:

• This method will require a database that will contain entries of all the email providers that you wish to add
• See to it that while making entries in this database, you do not add an entry more than one time, else the code if($mcount==1) will not work. (You may refine the code to >= 1, but haven’t tried it)
• Same code can be used to allow or block IP addresses by specifying the separator as ‘.’ (dot). The splitted strings can be stored in an array.

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