Speed of sending email .. can I put them in a queue rather than wait?

Hi all. I'm currently using the phpmailer class from phpmailer.worxware.com to send datatbase -populated emails to clients. At the moment I'm runninng PHP on Windows and using the built-in sendmail equivalent packaged with XAMPP. It uses a remote SMTP that authenticates by prior logging into a POP account. The number of emails sent is very small. Each one is only sent after a user fills out a form and presses send. But there is a noticable lag of about 5 or sometimes 10 seconds after pressing "send" before the user sees the "Mail sent" page. I presume the reason for the lag is the time spent logging on and off a remote POP, then SMTP server, transferring the data etc. It would be better if this happened in the background - that is, the user could get on with doing his next task while the emails sat in a queue in the backgorund, being lined up and sent without PHP waiting for the process to finish. Can anybody recommend a good way of doing this? Is Mercury Mail going to help me here?