Ki Song wrote: > Is there a way to limit the bandwidth used by postfix when sending/receiving > messages? > > The reason is that we sent out a newsletter, and the performance is > excellent, but it is using up all our bandwidth. I've not had to do this with Postfix, but I have with certain other MTAs. I assume your real problem is that it's slowing down other traffic, especially interactive traffic. In my experience, using all *available* bandwidth, in itself, is good. (You paid for that bandwidth: you might as well use it). And this is because most MTAs will open lots of outbound TCP/IP connections if they have lots of mail to deliver. These connections will swamp the other connections. The best solution is probably traffic shaping *on the router* that will prioritise other traffic over outbound SMTP. That isn't always available. As a "next best solution", I've found that limiting concurrent outbound connections [1] makes MTAs co-exist much better with other network services. I usually try three or four, and modify from there. As far as I can tell, you can do this in Postfix by editing /etc/postfix/master.cf, and changing smtp unix - - n - - smtp to something like smtp unix - - n 4 - smtp Note that with only one or two outbound connections, you can be slowed down by bottlenecks elsewhere on the Internet, or if you are unfortunate enough to connect to a misconfigured teergrube (http://catb.org/~esr/jargon/html/T/teergrube.html). Hope this helps, James. [1] i.e. limiting how many connections they have open at any one time -- E-mail address: james | My friend, you would not tell with such high zest @westexe.demon.co.uk | To children ardent for some desperate glory, | The old Lie: Dulce et decorum est | Pro patria mori. -- Wilfred Owen
