You could try MailSite: http://www.rockliffe.com/mailsite.htm.
We have many customers running the product with Emerald without any
performance problems. We also have many customers switching from NTMail.
Here is a recent message from one customer about Emerald:
From: Steve Williams
To: mailsite-discuss@rockliffe.com
Date: Thursday, January 29, 1998 6:19 PM
Subject: Re: MailSite and Radius
>>I am not using MailSite just yet but am interested in some stats and usage
>situations. I would be very interested to know your experiences relating
to:
>>
>>1. Using MailSite with Radius Authentication.
>
>With an Emerald database? Works perfectly.
Regards, John.
-----Original Message-----
From: Duane Schaub <dschaub@terraworld.net>
To: emerald@emerald.iea.com <emerald@emerald.iea.com>
Date: Thursday, February 05, 1998 8:37 AM
Subject: NTMail Performance
>I am getting poor performance from my NTmail/Emerald setup.
>
>NTMail is running on a machine with 128Mb ram/P200(Just a plain old 200)
>and IIS4 with a few domains. After running for a day or so, POP and SMTP
>occupy about 70-90 MB of RAM by themselves, and inetinfo user another 40Mb.
> It takes about 24 hours to reach these ram levels. Immediately after boot
>up, only about 71 Mb (including disk cache) is in use. I believe that the
>inetinfo size is due to IIS caching its web content.
>
>Anyway, SQL is on a different server p166/96Mb RAM. When a user checks POP
>mail, it takes 10-15 seconds for emer_ntm to retrieve the user info from
>the DB. It almost seems like it has to login to the SQL server or
>something like that. The SQL server only has about 10-15% CPU utilization
>and considerable idletime on the Harddrive. It appears to just be sitting
>there after the pop request has come in.
>
>Is this performance normal with NTmail? I have a number of users
>complaining that SOME of their incoming mail is bouncing back to the sender
>with invalid user errors. This is only some mail. Also, when checking pop
>mail sometimes users get "Invalid username/password". They can check again
>a few seconds later and it works. The problem is that some users
>immediately start playing with their system and screw it up. Then I spent
>the next half hour trying to fix them.
>
>Here's one for Dale.... Can you make an SQL script that will generate a
>file (like radius) that can bet run with the command line ntmail program to
>save the users to the ntmail registry. This will allow users to bypass the
>ntmail.dll and full utlilize the aliases, etc within emerald. If this can
>be done in an external program or as an SQL script, then I can schedule it
>to run periodically during the day. This will reduce the loading on the
>SQL server and reduce network traffic plus significantly enhance the
>reliability of the NTmail server since it won't rely on the ODBC
>connection... Which seems shaky at best.
>
>Duane.
>
>
>
>==========================================================================
>Duane Schaub, President |Terra World, Inc - Connecting The Planet
>Terra World, Inc. |Southeast Kansas' Leading Provider
>200 Arco Place, Suite 252 |Flat Fee - Never an hourly Charge
>Independence, Kansas 67301 |Where Service is Top Priority!
>Voice (316) 332-1616 |http://www.terraworld.net
>FAX: (316) 332-1451 |dschaub@terraworld.net
>===========================================================================
>