mario ovvauoptisolutionscoza hi mark phoned isp lowered mtu modem everything working fine thanks reply regards mario mark martinec wrote mario cisco routermodem esmtpsmtp inspection done isp guy told relay smtp server issue sending mail receiving mail example tried mail gmail account receive delivery failure message feb 26 131625 toeksie postfixsmtpd8286 timeout data nfout0910googlecom64233182189 firewall box route chance block icmp type 3 packets shouldnt otherwise path mtu discovery work type 3 code 4 tcp session hang times mark fri 08 aug 2008 062144 0200 timeouts