what is the best separator to separate multiple emails

Question

I am using mailto link to populate bcc of users default email program.

$mem_email=" ";    
$sql="SELECT email_address FROM employee";
$contacts = $db->query($sql);
while($contact = $db->fetchByAssoc($contacts))
{
    if($contact['email_address']!="" && $contact['email_address']!=NULL)
    {
        $mem_email.=$contact['email_address'].", ";
    }
}

header("Location: mailto:?bcc={$mem_email}"); 

My question is what is the best separator to separate multiple emails in bcc field , or ; .

In my case i am using ', '.

Answer 1

The separator should be a comma (,) and there should not be a space.

See RFC 6068.

Answer 2

Here's a late caveat in case anybody needs it:

Even though RFC explicitly recommends a comma, Microsoft Outlook will use the "list separator character" defined in the regional settings. Your mailto links may not work correctly for your Windows + Outlook users whose systems are configured with a different list separator such as semicolons. Outlook will simply refuse to split the e-mail addresses with commas.

Just something to keep in mind.

Answer 3

Use following code,

implode(',', $contacts);

above code will give comma separated emails.