On Fri, Jul 01, 2011 at 06:12:09PM +0100, Oliver Schonrock wrote:
> When using my php library I was able to isolate the delay to the
> END_OF_DATA command ie
>
> <CR><LF>.<CR>LF>
>
> Postfix's response to that command takes 0.1s if using the "Sendmail"
> client or the php library. but takes only 0.01s when using the postfix
> sendmail replacement library (note this is true when run from the host that
> postfix server is on or a machine which is on local Gbit LAN).
It the sending system's TCP stack that delays "." after the message body,
when the sending system does not implement SMTP PIPELINING, or does not
make use of all available SMTP PIPELINING opportunities. The Nagle algorithm
in TCP will delay a second (small) write when a previous write is not yet
acknowledged.
Use Postfix, it will not suffer unnecessary Nagle delays.
--
Viktor.
