It regularly happens that I want to schedule a mail to be sent at a certain time in the future. The ideal tool would also let me invite others to subscribe to this one time mailing, for example to remind people of the next Profoss, even if they don't want to subscribe to the newsletter.
If oyu don't find it, build it they say. Well, here it is: Taktiki.com.
And it's simple: no authentication is needed: created you mail, validate the sender address, and add recipients or invite people to subscribe to that one-time mail. For example, to get a reminder on monday for Profoss' ERP event on tuesday, you can subscribe here
In the hope this can help other people out there!
PS: for those who wonder: yes, that's the best I can do in web design. And that's with the help of YUI's CSS and grid help