Boost SMTP form sending speed with a mask

Hello. We have a hosting provider that does not accept sendmail, so we have to use SMTP in order to be able to receive contact forms from our website. The problem is that it takes too long (about 8 seconds) to be sent, probably due to SMTP authentication. A lot of visitor click on the "send" button, but do not wait its sending time. So we would like you to hide this ping time to the visitors, by immediately showing the message of "message sent". So the database would store the contact form information and send it to the e-mail by its own. Is this possible?