This week, my focus and task is to test email attachment parsing functionality of our project. In this module, we used the third part open source software-LumiSoft.Net to monitor some designated email account, in a infinite loop, this component will connect to the email server with the correct email user account and password supplied, when the email arrived inbound the mailbox, this component will read the mail and save the annexes of mail to local directory, then the contents of the annex will be parsed by another module. Not difficult, is not it? initially I did think so.

quickly I finished my code:

Pop3_Client client=new Pop3_Client();

client.Connect("emailserverIpOrDomainname","port",false); --the third parameter designates whether use SSL connection

client.Authenticate("validuseremailaccount","password",false);

...

The interesting thing begin to happen immediately after I deployed my app into LAN circumstance. The app can correctly connect to our company's external email server, exchange server2007 and get the attachments. but it failed when testing in company's internal email server, exchange server2003. The thrown exception said this account is prohibited to log on to this computer. At first, I suspected that it must be related to email server settings. but I can't figure out concretely where, since I am not familiar to network security very much. It turned out finally that it is company's network security strategy causes this problem. Then internal LAN is based domain, the staff no of each emplyee is banged with his computer and it is not allowed that some employee log into the domain from other computer with his staff no. and the email server assigns every employee email account using his staff no, but on the email server, there is an option stating that this account which happens to be the account I used in code to connect to internal exchange server is allowed only.

This is a good lesson. I think.