envío, aunque quizás resulte excesivamente largo el texto, la respuesta total obtenida. gracias:
root@portalmw:/# sudo lsof -i | grep smtp
smtpd 1797 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 1797 postfix 9u IPv4 212206070 0t0 TCP portalmw.com:submission->ip-113-76.4vendeta.com:11260 (ESTABLISHED)
smtpd 2546 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 2546 postfix 22u IPv4 212229272 0t0 TCP portalmw.com:submission->141.98.80.73:2044 (ESTABLISHED)
smtpd 3729 postfix 6u IPv4 184027531 0t0 TCP *:smtp (LISTEN)
smtpd 3736 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 3736 postfix 9u IPv4 212275591 0t0 TCP portalmw.com:submission->ip-113-76.4vendeta.com:44060 (ESTABLISHED)
smtpd 4115 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 4115 postfix 9u IPv4 212276769 0t0 TCP portalmw.com:submission->141.98.80.73:21098 (ESTABLISHED)
smtpd 4251 postfix 6u IPv4 184027531 0t0 TCP *:smtp (LISTEN)
smtpd 16490 postfix 6u IPv4 184027531 0t0 TCP *:smtp (LISTEN)
smtpd 16490 postfix 9u IPv4 212138070 0t0 TCP empresadetrabajotemporal.com:smtp->mta1b5-booking.mta.e.sparkpost.com:9167 (ESTABLISHED)
master 22555 root 12u IPv4 184027531 0t0 TCP *:smtp (LISTEN)
master 22555 root 109u IPv4 184027627 0t0 TCP *:ssmtp (LISTEN)
smtpd 23313 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 23313 postfix 9u IPv4 212211036 0t0 TCP portalmw.com:submission->111.90.168.203:35374 (ESTABLISHED)
smtpd 26295 postfix 6u IPv4 184027531 0t0 TCP *:smtp (LISTEN)
memc 29574 www-data 6u IPv4 212287831 0t0 TCP portalmw.com:45962->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 8u IPv4 212287829 0t0 TCP portalmw.com:45960->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 9u IPv4 212287836 0t0 TCP portalmw.com:45967->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 10u IPv4 212287830 0t0 TCP portalmw.com:47205->idcmail-mo2so.shaw.ca:smtp (SYN_SENT)
memc 29574 www-data 12u IPv4 212287834 0t0 TCP portalmw.com:45965->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 16u IPv4 212287832 0t0 TCP portalmw.com:45963->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 17u IPv4 212287835 0t0 TCP portalmw.com:45966->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 19u IPv4 212287833 0t0 TCP portalmw.com:45964->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 20u IPv4 212287837 0t0 TCP portalmw.com:45968->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 21u IPv4 212287838 0t0 TCP portalmw.com:45969->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 22u IPv4 212287839 0t0 TCP portalmw.com:45970->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 23u IPv4 212287840 0t0 TCP portalmw.com:45971->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
memc 29574 www-data 24u IPv4 212287841 0t0 TCP portalmw.com:45972->idcmail-mx2no.cg.shawcable.net:smtp (SYN_SENT)
smtpd 30708 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 30708 postfix 9u IPv4 212043506 0t0 TCP empresadetrabajotemporal.com:submission->141.98.80.73:58334 (ESTABLISHED)
smtpd 31274 postfix 6u IPv4 184027632 0t0 TCP *:submission (LISTEN)
smtpd 31274 postfix 9u IPv4 212075497 0t0 TCP portalmw.com:submission->ip-113-76.4vendeta.com:56622 (ESTABLISHED)
root@portalmw:/#