Sendmail 'Too many connections' problem

[Paul Howarth]

Steven W. Orr wrote:
> I run sendmail-8.13.8 at home to host my domain. Some domains will not 
> accept mail from me because my address is from a dynamic address pool so 
> I solved that problem by placing all of those domains in my mailertable 
> and now route those messages through my ISP(RCN). Recently I have 
> noticed that some of the mail is hanging for a while with 400 series 
> messages saying 'Too many connections'. I checked with RCN and after 
> many wasted hours on hold I found out that I need to limit the maximum 
> number of connections to their SMTP server to 4. Four shall be the 
> counting. Five is too many and six is right out!
> 
> Can someone please tell me what the incantation is to limit the number of
> simultaneous connections to a particular server? I'm not looking to 
> limit incoming conncetions. I'm not looking to limit the rate of 
> incoming or outgoing connections. I just want to set the max nr of 
> connections from me to RCN to no more than four.

Looking at the holy README file of Antioch in the sendmail-cf package, 
it appears that setting confHOST_STATUS_DIRECTORY and 
confSINGLE_THREAD_DELIVERY will have the result of limiting outbound 
connections to any one host to 1. Whilst this is not 4, it's likely to 
at least get your mail delivered eventually.

Paul.