InterForm400 SMTP is selected as described here. You can chose either:
2=IF400 SMTP
Use the InterForm400 SMTP instead of the IBM SMTP. It requires that the MAILINTER subsystem is running and that the System i is able to reach internet to e-mail itself or via the E-mail gateway.
3=IF400 SMTP (register only)
All e-mails sent from InterForm400 are not sent immediately but only registered. This can e.g. be used for testing. You can then at a later time (e.g. at night where the bandwidth is most probably not used) send all pending e-mails with the command APF3812/SNDMAILS. You can view the registered mails via the email log.
4=IF400 SMTP (batch)
With this option the sending of the email is submitted as a batch job in the MAILINTER job queue. This enables faster emailing and the user experience is better for the interactive emailing as the email commands returns immediately and submits an email job instead of trying to communicate with the email server directly. This option use the InterForm400 SMTP instead of the IBM SMTP
2=IF400 SMTP or 4= IF400 SMTP (batch) is recommended for most installations.
Note, that the APF3812/MAILINTER subsystem must run in order to make automatic retries possible (only available for InterForm400 SMTP). You should consider to start this subsystem during IPL e.g. via the QSTRUPPGM program (or link startup with the AUTO_FORM subsystem as described in the configuration), if you use InterForm400 SMTP. Refer to the commands APF3812/ENDMAILSBS and APF3812/STRMAILSBS for details.
If you want to use a user and password and/or SSL/STARTTLS, then you should press F8=Gateway security on the SMTP configuration screen.
You can also specify multiple SMTP gateways via F20=Alternative gateways on the SMTP configuration screen.
