ISP-Planet: Webmail Directory: AtDot

“AtDot was first written in 1998. At the time, Jakob Kaivo, the
project’s developer, was working for an ISP that wanted to provide
a simple webmail offering to its customers. ‘There were no open
source webmail programs—at least that we were aware of–so I
volunteered to do it in-house,’ Kaivo says.

“When Kaivo first created it, he says, AtDot was a very simple
POP3-based client. ‘Authentication was performed against a POP3
server, or you created an account which in turn authenticated
against a POP3 server,’ Kaivo says. ‘There was only access to your
Inbox–but you could also send messages, including replying to and
forwarding messages from your Inbox.’