Kelly, Your intuition has already told you to either (a) get huge mail blasts off a server that's under load as quickly as possible, or (b) never send them through your mailbox server at all. Your best-fit solution depends on the priorities you give to OS standardization and support, raw throughput, and single-server integration.
No matter what, you're going to want another box besides your Imail server to help you out. There are huge performance advantages to offloading remote SMTP sending and DNS resolution to a dedicated box, called a Smart Host. The advantages apply to all mail servers regardless of platform, but do apply particularly to Imail in light of its process-centric (rather than thread-centric) architecture, a development choice that really makes its handicaps known when you dump a lot of bulk mail...HOWEVER, these process-related handicaps are negligible when you use Scott Perry's great Declude products for Imail, www.declude.com, which include a new queue manager, in conjunction with a Smart Host. So on to your choices. For each, figure on a dual-processor PIII Xeon at 400 Mhz+ with at least 256 MB RAM and a RAID 1 array with 64 MB+ of controller cache. You don't need all the RAM for the *nix options due to the low OS overhead, but for the negligible price these days it couldn't hurt to standardize the hardware (if you're a Windows shop, RAM is probably already a given). 1) IMAILSRV/MSSMTP: If you're standardized on Windows architecture and want to keep all of your list administration tasks within the Imail GUIs (web and Windows), and you're comfortable with the functionality of Imail's built-in list server, IMAILSRV, put up your second box on Windows 2000 (Pro is OK) with IIS 5's SMTP server. Microsoft's SMTP Server for IIS 5 is actually enterprise-capable, multithreaded, SMP-aware, etc. I find it underrated, since it's free, runs on cheapish 2K Pro and serves the Smart Host purpose excellently. Also make sure you're running Declude to take advantage of its queue management. 2) IMAILSRV/POSTFIX: If, again, you're cool with IMAILSRV as your MLM but want the fastest possible performance from your Smart Host-driven architecture and are comfortable supporting a *nix OS, put up the second box on Linux or BSD and install PostFix. PostFix is faster than Microsoft SMTP and can do more with less hardware, like most *nix-based products. Len Conrad has prepared an installation guide for PostFix/Imail integration he calls IMGate (http://IMGate.MEIway.com) that would help you here. Here too, make sure you're running Declude with Imail. 3) LISTAR/POSTFIX: If you don't need a single-OS, nor an Imail-integrated solution, and are disappointed with the list management capabilities of IMAILSRV, you can put up your second box on *nix, install PostFix, and install a *nix-based mailing list manager (MLM) such as Listar (www.listar.org, soon to be renamed Ecartis) that sends though the local PostFix MTA. In this config, Listar is maintained completely separately from Imail, but gives you a lot more functionality than IMAILSRV. You could also use the same PostFix installation as Imail's Smart Host for user mail, or segregate the systems entirely. Write back if you need more elaboration. I do note that you've started a new thread in the meantime which seems to suggest an outsourcing move, so I don't know if this post is relevant anymore...but there it is! Regards, Sandy P.S. I would be remiss if I didn't mention a fourth solution that's on the horizon. My firm (Broadleaf Systems) has a team working on a full-featured replacement for IMAILSRV that will give Imail Ecartis-level functionality on-board. Some of our functions, all absent now from IMAILSRV and some even from Ecartis, include: - Subscribe/change/unsubscribe confirmation - HTML, Return Receipt Request, PKI, and oversize rejection/stripping - Automated bounce message processing - Handshake-only (simple) and full-text (thorough) membership probes - ODBC membership lists, synchronizable with ODBC domain userbases - Multiple moderators - Backward compatibility with IMAILSRV lists, or optional conversion Despite its relevance to your situation, the release of our product in 2002 will no doubt be too late for your needs. I mention it here so that you might "pencil us in" and be sure to check back with is if you have any issues with the solution you do choose. Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/
