ASP.NET "5.7.1 Unable to relay for email" when SmtpClient.UseDefaultCredentials = true

Was looking at a problem with Andy regarding using SmtpClient.UserDefaultCredentials = true, and sending emails within an authenticated WCF service.

We can send emails within the domain without any issues, but when sending emails outside of the domain the mail server rejects us with the 5.7.1 Unable to relay for email@external.com

The easier fix would probably be to UseDefaultCredentials = false, and specify a NetworkCredential(username,password).  But we were stubborn and didn’t want to have to enter a email address somewhere in the web.config.

While investigating – we realized that if we specify the mail server by IP address instead of DNS name – then the email will be delivered.

Our suspicions are that the Exchange mail server has different rule sets to decide if it trusts the source to be somewhere local.  If the IP address specified is a local network IP – it seems to relax the relay rules somewhat.

SharePoint 2010 Speed, and Boot to VHD

Been pouring through all the new goodies in SharePoint 2010 like a kid opening his first Christmas present -
So much fun, so little time.

A few people have made the comment that SharePoint 2010 Public Beta runs pretty slowly for demo’s – here’re a few suggestions I’ve noticed that helps for me:

1. You need more than 2GB of RAM for SharePoint on your demo machine. 
2. Ideally, a generous amount of hard drive space

My setup has worked pretty well for me:

1. Host is Win7 x64
2. Created a VHD (virtual hard drive) with about 50GB allocated space. 
3. Installed Windows 2008 R2, SQL Server 2008, SharePoint 2010 public beta, Office Web Apps, and Office 2010 client apps.
4. Configure the VHD as a bootable device (new in Win7)
5. On start of laptop, I get to choose to boot into Windows 2008 / SharePoint 2010 directly, which allocates all the laptop’s resources to the VM
6. Oh – grab the ATI display drivers for DELL (see my previous post) to make sure Windows 2008 R2 can display via an external projector – ahead of the presentation.  (I nearly had a panic attack but got it all sorted before I had to go on stage).

The best part is when we move on from the public beta, I’ll just copy a new VHD over the same directory under Win7, then it’s all set.

ATI x64 driver fail - Catalyst Install Manager has stopped working

This could possibly be the last ATI product that I'd purchase.  For almost as long as I could remember I can not get the ATI drivers to install.

• Download from ATI website
• Download beta from ATI website
• Download from Dell website

I've always had to rely on Windows Update - but then it doesn't come with the Catalyst utilities.

Today I was forced to upgrade the drivers...

• Running Boot to VHD on the machine with Windows Server 2008 R2 x64 installed
• Default driver that Windows Update picked up is the Generic one
• I need to be able to use an external monitor for presentation tomorrow - Yikes!

Fortunately, I found my solution here:

http://insomniacgeek.com/blog/catalyst-install-manager-has-stopped-working/

To cut a long story short - this worked for me:

bin64\ATISetup.EXE –install –output SCREEN