[Q] what is different of mail sending (sendmail) between HPUX and Solaris ??

[Tony, Lim]

All,
Would somebody let me know what different of mail sending between HPUX and Solaris is ?
I have several unix servers and some are HPUX 11.11 and some are Solaris v8.
To use "mailx" command in maintenance scripts, I set a relay server in sendmail.cf of /etc/mail.

What I'm curious is
,in HPUX, "mailx" is working without sendmail daemon. but in Solaris, "mailx" is not working without sendmail daemon.

I'm not good at those sendmail site. my knowldge of UNIX is very general, not specific and expertized. so need your help.
Why it works without daemon on HPUX, and why not on SUN which is not working sendmail daemon ??

[Dennis Handly]

We can't help you here about Solaris, it just is different. And will get the thread removed.

But on HP-UX, you only need sendmail to receive mail. mailx automatically invokes sendmail to send it. See SEP's reply in this thread:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1216340

[Matti_Kurkela · Accepted solution]

In HP-UX, the tools like mailx may work without the sendmail daemon running, but they won't work reliably.

The reason: in HP-UX 11.11, mailx runs sendmail in "one-shot" mode. In this mode, sendmail makes _one_ attempt to send the mail to the recipient. If all works well, this is enough and the mail is transferred successfully.

But whenever there are any problems (recipient's mailbox full, recipient's mail server is offline for maintenance, network problems, etc.) the mail is stored to /var/spool/mqueue so that the sendmail daemon can re-send it. If sendmail is not running as a daemon and the sysadmin has not done something to make sure the mail queue gets emptied, the mail remains forever in /var/spool/mqueue.

I've not maintained any Solaris machines in a few years, so my Solaris knowledge is a bit weak. But apparently the mailx of Solaris will attempt to connect the running Sendmail daemon instead of using the "one-shot mode". If there is no sendmail daemon running, this will of course fail.

With HP-UX 11.11 and older, if the sysadmin wants to disable the sendmail daemon, the standard workaround to the mail queue problem is to make a cron job that periodically runs "sendmail -q". This tries to re-send any messages trapped in the mail queue, and generates bounce messages for those mails that have been stuck in the queue for too long.

HP-UX 11.23 and newer are using an updated version of sendmail that splits some of the sendmail's tasks into a separate "sm-client" process. These versions can easily be configured to "send-only" or "receive-only" modes using the settings available in /etc/rc.config.d/mailservs file.

MK