Can't receive incoming email

[barrycork]

I have just gone from an NT4/Exchange 5.5/Proxy 2.0 Domain to 2003 Server with Exchange 2003 and ISA 2000 however I cannot receive incoming mail from the internet. I can send out without any issues.

My existing Exchange install sits on the same box as proxy 2.0. We have replaced this with a 2003 Exchange Server and ISA Server on a seperate machine.

The ISA Internet facing NIC has the same IP as the previous Proxy 2.0 box so there should be no need to adjust the MX record at the ISP's DNS. As the exchange server is now sitting behind ISA we have configured a forwarder to the Exchange 2003 server from the ISA server so that incoming mail is passed on. We know this works as we can telnet the Exchange server from behind the ISA server without any problems. Our ISP is also able to telnet our exchange 2003 Server without issue.

I am stuck as to what we should try next.

Any help/suggestions would be appreciated.

Thanks,

Barry

 

[barrycork]

I solved the problem. On ISA 2000 server the default maximum NOOP walue on the SMTP filter is set to 6 bytes. Exchange 2003 does not like this. For incoming mail to pass through the ISA server the NOOP walue must be increased to 38 bytes. After doing this the mail starts to flow.

Barry.

 

[lockportmarc]

Barry,

Where did you change this setting? Someone was having problems receiving email from us and mentioned that they had to increase the size of NOOP to 20 to get it flowing correctly.

They said that the standard is 6 bytes and somehow we were padding ours. Does that make sense? We have Exch 2000 now and will be upgrading to 2K3 within the next month.

Thanks,

Marc

 

[barrycork]

Marc,

The NOOP setting on ISA2000 is in the following location;

Extensions - Application Filters - SMTP Filter

Right click the SMTP filter and select properties before selecting the SMTP Commands tab.

You will then see the NOOP value which you can edit. I changed mine from the default of 6 to 38 after which the mail started to flow.

Cheers,

Barry