A:  This matter is documented in the iSeries Information Center, in a page carrying the title Authenticating e-mail for local and relay (search for "spam").

What is the problem?
The open relay feature on SMTP servers allows abusers of SMTP to send hundreds unsolicited e-mail to large, indiscriminate distribution lists. The abuser can masquerade the sending address so that it appears that the spam originates from a false address (inside or outside the local mail service). The falsified address hampers your efforts to determine the source of spam.

How do I fix it?

• Up to V4R5
  You fix it by specifying in a source member what are the IP addresses allowed to use the open relay feature of your SMTP.
  Do the following:
  1. crtsrcpf file(QUSRSYS/QTMSADRLST) ccsid(500)
  2. strseu srcfile(QUSRSYS/QTMSADRLST) srcmbr(ACCEPTRLY)
  3. type a line as follow:
     tcp_address_of your_AS/400  255.255.255.255
     and exit from SEU
  4. endtcpsvr *smtp
     strtcpsvr *smtp
• From V5R1 on
  Do the following:
  1. chgsmtpa alwrly(*list)
  2. addsmtple type(*accept) intnetadr('n.n.n.n')
     where n.n.n.n is the IP address of your AS/400
  3. endtcpsvr *smtp
     strtcpsvr *smtp
  Note. If you are coming from V4 and you already used the anti-spam technique, just enter command
        chgsmtpa alwrly(*list)
  and restart SMTP.
  File QUSRSYS/QTMSADRLST is read from SMTP, its records converted to "smtp-list-entries", and the file is deleted. This is why, if you try to enter the above command
        addsmtple type(*accept) intnetadr('n.n.n.n')
  you get the message "duplicate entry".

How can I find out the IP addresses allowed so far?

• dsppfm qusrsys/qatmadrlst acceptrly