asp.net email +Transaction failed. The server response was: Sending address not accepted due to spam filter

A very common error while sending email through ASP.Net code :
"Sending address not accepted due to spam filter"
To resolve this just pass the network credentials for a user and it will work.

FileUpload control does not work in Update Panel : solution

All file upload controls (includes asp, telerik, componentart, component factory and others) does not working in any AJAX update panels. This means if your upload control located in an update panel, control does not post the file. If you look to the posted file property of the control, you will see it null.

This is a limitation comes from the XmlHttpRequest component, used in all AJAX frameworks for asynchronous calls to the application. In order to upload a file you should perform a full page postback.

The solution is to add a Triggers tag:

<asp:UpdatePanel ID="upFileUpload" runat="server" >

<Triggers>

<asp:PostBackTrigger ControlID="btnUpload" />

</Triggers>

<ContentTemplate > .....

</ContentTemplate>

</asp:UpdatePanel>

See it work like a charm!!

Issue with the ajax tab panel

In case your AJAX Tabs are not rendered properly and you get white line/space then quick fix will be to define the height of Tabs.

Define the following CSS below and reference in your TabContainer and things will work well .

<style type="text/css">

.ajax__tab_xp .ajax__tab_tab

{

height: 21px;

}

</style>