Can I create an email proxy?

[qchpmb]

I have a problem that I hope an email proxy can take care of but I
need some advice

We are moving our small office and have 4 users using OE that connects
to pop3 from our cable provider (optonline.net)

The new office is verizon fios and I will eventually switch our email
accounts (actually going to MS Exchange), but for the move I just want
to keep our email the same (optonline.net)

I have VPN routers at both locations and have managed to create a site
to site vpn that connects both networks together but the problem is
that when trying to send email from the verizon network using the
optonline.net accounts that cablevision blocks port 25 from a non
optonline network (no relay I believe).

The router at the new office routes internet traffice out through
verizon and only 10. traffic across the VPN so I'm stuck in this
situation.

Is it possible to put a windows based proxy on a computer at the old
office that the OE clients at the new office will send and receive
mail through which will then send it out throught the optonline.net
network and allow me to keep everyone running until I get our new
server running with exchange and have an orderly switch to a new
domain name?

winproxy or something similar? I've just started looking into this
but it seems like it would work.

Need to know if it's possible, and suggestions would be great as to
what product I could use. Thanks and I appreciate the input.

Regards,

Roveer

 

[qchpmb]

This is a very common problem. ISP's don't usually allow mail to be
sent through their smtp servers from outside their network, they refer
to it as realying and is often used by spammers who comprimise others
email accounts. They of course offer web access email as an
alternative to those who are outside the network. Can't give my
people web access when they have been using OE for so long. Of course
most ISP's allow you to receive mail via smtp from outside networks.

So far today I've come up with two workable solutions (with help from
others on the SBS group)

1. SMTP Proxy software on a PC on the optonline.net network
(Installed it and it works)

2. Receive Mail from Optonline.net from the verizon network (works),
and send mail through the verizon smtp servers (configuring OE to use
(e-mail address removed) as the reply to address). Haven't tested this yet
as I don't presently have any defined verizon email accounts, but will
test this from home tonight from my patmedia.net isp. In theory this
should work and may be the easiest method as it only requires changing
the "reply to" line in OE and specifiying the verizon smtp address
with login credentials (I have to also make email accounts for the
users), in OE and I'll be done. No proxy servers to run etc.

Does anyone know of any good free smtp proxy software? I tried
wingate (works, > 100 bucks) and postmaster (works but out of business
and it's on a 90 day trial)

Roveer