Our company uses webmail so the guys/girls out and about can log in to their emails using any PC.

If I log into webmail whilst in the office then it is lightning fast however I am getting reports that logging in from outside it is very slow - I have checked this myself and it logs you in ok but then takes a while to get to your inbox and seems very sluggish.

I've checked and nothing seems amiss on the server. (The server is running Windows Server 2003 and Microsoft Exchange Server)

Any thoughts?

Are people uploading/downloading a lot over you pipe?

If somebody is sending big files outside or you have a lot of people connecting at the same time (lots of remote desktop sessions, for example), it could be sapping your bandwidth.

how is your firewall server looking? Is that being hammered?

We have 4 broadband lines all running around 6500kbps.

Incoming and outgoing internet & mail uses the same line so I might switch it so "in" uses 1 line and "out" uses another to see if that changes anything.

The firewall shows a lot of traffic from a main server to Zen dns servers (email and internet I assume?) as well as port 137 - which could well be our Blackberry Server as I did an IP lookup (82.132.139.186) and that came back as O2.

I'd imagine that's the download speed, the upload could well be about 10% of that. I'd have a quick look at your outbound traffic.

That would probably break things (as the reply would come from a different IP)

Why would that matter, so long as the MX and SPF records are amended accordingly? You can assign as many IPs as you like, or are you not talking about the email? I was assuming that's what "John" meant.

Personally, if I had 4 ADSL connections I'd examine the usage very carefully. The remote OWA users, as Coref pointed out, need upload bandwidth. I'd simply assign the OWA URL to the connection with the most free upload speed. Setting up the routing might be quite fun though, depending on the topology.

How exactly are the 4 lines assigned right now? If in/out email and web browsing currently share the same line, what are the other 3 used for? You have plenty of room to balance the loading favourably.

Found the source of the problem.

On the exchange server we also have running an FTP program - I checked and for some reason it was trying to run twice.

I turned off the duplicate one and webmail is now nice and snappy again.

Weird.