I am a webmaster. I have Infacta Group Mail installed in which around
3000 recipients are subscribed. I daily have to send them emails which
takes upto 1 hour due to slow internet speed. In all emails I have to
attach either "HTML" content or "attachments" of *.gif files. I want
to move from manual work to automation.
What I want is that all of this should move to my hosting on the web:
subscribers data will be kept on the web, material to be sent be also
on the web folder. A set time at which that webserver automatically
compiles the email with attachment and other material and sends it to
those subscribers.

I will be grateful If I am told about such installable script on the
web. Please and thanks a lot.

I am unsure of a program that currently does it but if you have the
ability to run cron jobs and php programs I could quickly whip up a
program that could do it.

Why not install your own auto-responder? There are many available and
some are free. Most of these are CGI programs that are not to
difficult to install and I think will handle exactly what you want to
do.