On Sun, Apr 30, 2023 at 06:06:48PM -0500, Matthew McGehrin via Postfix-users wrote:
> You can try adding to your main.conf: > > tcp_windowsize=65535 > > See also: > > https://www.postfix.org/postconf.5.html > > That can help fixing broken window sizes because of a firewall. This won't help. The choice of TCP window size can sometimes play a contributing role in problems during message *transmission*, but not during TCP connection setup. [ TCP fast-open aside, the SYN and SYN-ACK packets carry no data. Postfix does not enable TFO, and it is not on by default. ] The OP may be on a network that is blocked by the receiving system, or from which SMTP connections are filtered by the local provider. -- Viktor. _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
