Re: open(FH,'|qmail-inject') fails

[Andrew Dunstan]

Regarding cost of forking etc.:

Your mileage will undoubtedly vary, according to OS and MTA.

Last time I did work on this was about a year ago on Solaris 
2.6, with sendmail and postfix. In both cases using Net::SMTP 
was far faster. IIRC, with postfix there is no forking cost at all, 
as its daemon does not fork on connect (it uses a select() loop 
instead). Talking on the SMTP port is actually Wietse Venema's 
recommended method for fastest injection into the postfix queue.

It also has the advantage over other methods that it is totally 
MTA independent.

andrew