Smtp_out very slow external domains

Question

I have ocs 10.1.2 on Red Hat Enterprise Linux ES release 4 (Nahant Update 2)
When I send mail to external domain
smtp_out is very slow to close session
When I send 2 mails to the same outside user, the second mail is very to be delivered
because smtp_out try the last session wich is closed by the remote host.
My ocs is directly connected to Internet so no relay needed.
OCS / External Domains
SYN -->
<--- SYN
PUSH --->
<---PUSH
<----FIN
15,30 minutes later
FIN ----> (I supposed ignored by the remote server)
Think you

Answer 1

OiDAdmin / Directory Manager:
Entry Management, OracleContext, Computers, midtier, midtier ORACLE_HOME,
EMailServer, mailprocessconfig, smtp_in:
Right hand site, click on "All" attributes.
Change: orclmailsmtpminqueueage from 30 to 1
Add: orclmailsmtpminqueuepollinterval: 10
Entry Management, OracleContext, Computers, midtier, midtier ORACLE_HOME,
EMailServer, mailprocessconfig, smtp_out:
Right hand site, click on "All" attributes.
Change: orclmailsmtpqueuepollinterval: 120 to 10.
orclmailsmtpconnectionnumber: 30 to 0 (yes you read correctly)
orclmailsmtpminqueueage: 30 to 1
Stop and restart both smtp_in and smtp_out.