On 12/16/2012 9:56 AM, mouss wrote: > Le 15/12/2012 14:43, Ram a écrit :
>> If I have to use a single IP for a sender domain to the internet, but >> yet the mails may get sent from different servers >> What is the best way for doing it >> >> The requirement is because the volumes are too large for a single >> machine to handle but the client still wants to send the mails using a >> dedicated IP A properly configured Postfix server can send many hundreds, even thousands of msgs per second in parallel assuming receivers don't throttle the connections. As John Levine saliently pointed out the limiting factor in SMTP mail throughput is normally queue disk random IO rate--not CPU, not RAM, not network B/W nor latency. Put this customer on his/her own dedicated box with a single public IP routed to it, use a quality SSD, Linux, and the XFS filesystem, and you should be good to go. A 100Mb/s link can carry about 1400/2800 msgs/sec at 8KB/4KB msgs and properly tuned hardware+OS+Postfix should be able to hit this throughput. That's 84,000 msgs/min, 5M msgs/hour. At these rates receivers will likely be heavily throttling connections anyway. Does this client really need this level of throughput? > if the servers perform heavy tasks such as malware and spam filtering, > then dedicate one box to mail routing and use it as a gateway from which > all mail will get out. Exactly. And the configuration above should handle such gateway duty easily. > if even mail routing is too heavy, then as said, NAT may help (whether > on a hard box or on a server with BSD+pf or Linux+iptables), provided > one box can route as much traffic! Which begs the question: What's the actual message rate you're targeting here? You're telling the experts on this list that one box can't handle the load, but provided no numbers, no data, supporting this assumption. As I stated above, Postfix can sling over a thousand msgs/sec on a relatively low end but properly configured single box with SSD queue disk, and cooperative receiving MTAs. > Note1. with 1 IP, you get less than 2@16 ports, which gives a hard upper > limit on the number of simultaneous TCP connections. The default process limit is 100 smtp processes. Even if one had to bump this to 800 to achieve a desired msg rate (unlikely), I don't see Postfix consuming ~65,000 ports. Maybe I'm missing something. > Note2. if you need a lot of bandwidth, then the box that sends mail as > well as all other nodes in the path need to be able to handle this. Unless he's pushing more than 1400-2800 msgs/sec (8KB/4KB) then this probably isn't an issue as this is fast ethernet rate. Any modern business class router/switch/firewall can handle this rate without breaking a sweat. Of course our advice would be a lot more on target if the OP were to provide some kind of msg rate figures. One would think such information would have been provided up front with such a help request. -- Stan
