Why are emails sent to some addresses not arriving
There are a number of reasons that emails may not arrive or appear not to arrive. Often its just over zealous spam filtering especially by services such as Yahoo and Hotmail. Its always a good idea to warn users to whitelist your email address anyway.
By default Sitelok uses PHP's mail() function to send email but you can try using the PHPmailer method which can be more reliable. To enable this go to Tools - Configuration - Email settings and set Send email using to PHPmailer. Enter the SMTP server account details for the email address set in Admin Email. You can always set a Reply-to override if you need to. Make sure that the email address you have in Tools - Configuration - General settings - Admin Email is the email associated with the SMTP settings.
Contact us for help if you still have problems getting emails to be sent.