IIS Email Server Bouncing good email

[tlhawkins]

Hey,

Something went wrong with an IIS SMTP email server I'm working on. It has been sending email correctly for some time with no problems other than being a bit slow sometimes. Last friday it started bouncing all kinds of email that should go through. It doesn't bounce 100% of the time, but much of the email going out is bouncing. Even email directed at the same domain is sometimes bounced.

Does anyone have experience with this, or know of a way to track down or solve the problem?

Thanks

Travis Hawkins

http://www.bestcodingpractices.com

 

[WhoKilledKenny]

Hey Travis could you provide more information?

Bounce? meaning it is putting mail in the bad mail folder?

Is the IIS Box used as a gateway for an Enterprise Email system such as Exchange?

Are you using smart hosts to relay mail from IIS to your Email system?

Do you have errors you can post?



Jesse Hamrick

http://www.powershellpro.com

 

[tlhawkins]

Thanks for taking a look at my problem.

The email is ending up in the Bad Mail Folder. I also have it set through IIS to send me an email when an email fails so I'm getting these emails:

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

       customercare@mydomain.com

Where mydomain.com is the domain that is sending the email.
They are not ONLY failing to mydomain.com though, they are failing to many different domains with email addresses that I'm sure are correct.

any ideas?

Travis Hawkins

http://www.bestcodingpractices.com

 

[WhoKilledKenny]

Any Ideas? This is outgoing mail, check that your smtp server is able to do DNS Queries on the Internet.
from a command prompt on the SMTP server type the following commands:
c:\>nslookup microsoft.com

You should get something like:
Non-authoritative answer:
Name: microsoft.com
Addresses: 207.46.197.32, 207.46.232.182

Another Idea - Check that the outgoing mail security is set to "anonymous" on the SMTP Server.

From outside your company can you connect to your mail server? From the outside using a command prompt:
C:\>telnet yourmxrecord.com 25

Check you firewall for changes where port 25 could be blocked.

If you are running McAfee Anti-virus on the SMTP server make sure it is not blocking port 25. It does this by a setting that protects computers from mass email worms.

There are some ideas just off the top of my head...

Jesse Hamrick

http://www.powershellpro.com

 

[tlhawkins]

Jesse,

The only thing on your list that got a hit was the access into port 25. We have inbound port 25 blocked because the CBL (spam list) listed us for having that port open. When we blocked that port inbound they took us off the spam list.

Are servers doing a backward DNS on port 25, or do they just do it on the domain name? We receive email through a different server so this one doesn't need any kind of inbound email, it just needs to be able to send email.

Thanks again for taking the time to help me work through this problem.

Travis Hawkins

http://www.bestcodingpractices.com

 

[WhoKilledKenny]

DNS queries on port 53.

Jesse Hamrick

http://www.powershellpro.com