Application fails to send email with attahments

Question

I have an application that emails reports as attachments. it works in all clients' sites except for one. i am using a gmail account there. all the settings are right, outlook express can send email using the same account on the same network. a smtp diagnostic tool also send email, funny thing is our application times out. i used a simple packet capture tool, with the smtp diagnostic tool it shows how a connection to gmail server is being made, but when i am capturing with our application it does not appear to be even attempting to make any connection to the gmail server. process monitor shows its making the connection to the host (aka the server itself) on port 2578. its a windows server 2003 machine hosting the application which was written using VB & .NET 3.5. I am completely at a loss at what to try next. any ideas?

all ports are open, i have checked. and same result on our application with the ISP's email account too.

Thanks.

Answer 1

Let me try this one :

(?) So basically you are saying on your CLIENT unit the APPLICATION times out, whereas on all other client units it works fine ? I am trying to wrap my head around how this system works.

(?) So the application sends an email with attachment through/over gmail ? This app was written by you.

If this only happens on the client machine and if only this application on the client machine is affected, then I can safely assume that :

1.) Check the firewall settings on this unit for this specific application. You need to either add this application to exceptions AND add the port as safe.

2.) Check your SMTP port 25 and also 587. See if these ports are not blocked on the host machine OR only have EXCLUSIVE access to another application. The idea is to find an application that literally SITS on these ports and doesn't allow any other application to traffic through

3.) Check your anti-virus options and see if not maybe the port is blocked on that application. If you have Kaspersky installed on that client unit then disable it and see if that makes a difference. Uninstall and Re-install it if may be. Had doezens of cases where network issues and ports were blocked because of Kaspersky.

4.) Check on your server and router and the client traffic permissions. Maybe on the server or router it blocks traffic for this specific unit only. Also check policies and application usage right policies.