1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3 4<html> 5 6<head> 7 8<title>Postfix and Linux</title> 9 10<meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> 11 12</head> 13 14<body> 15 16<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix and Linux</h1> 17 18<hr> 19 20<h2> Host lookup issues </h2> 21 22<p> By default Linux /etc/hosts lookups do not support multiple IP 23address per hostname. This causes warnings from the Postfix SMTP 24server that "hostname XXX does not resolve to address YYY", and is 25especially a problem with hosts that have both IPv4 and IPv6 26addresses. To fix, turn on support for multiple IP addresses: </p> 27 28<blockquote> 29<pre> 30/etc/host.conf: 31 ... 32 # We have machines with multiple IP addresses. 33 multi on 34 ... 35</pre> 36</blockquote> 37 38<p> Alternatively, specify the RESOLV_MULTI environment variable 39in main.cf: </p> 40 41<blockquote> 42<pre> 43/etc/postfix/main.cf: 44 import_environment = MAIL_CONFIG MAIL_DEBUG MAIL_LOGTAG TZ XAUTHORITY DISPLAY LANG=C RESOLV_MULTI=on 45</pre> 46</blockquote> 47 48<h2>Berkeley DB issues</h2> 49 50<p> If you can't compile Postfix because the file "db.h" 51isn't found, then you MUST install the Berkeley DB development 52package (name: db???-devel-???) that matches your system library. 53You can find out what is installed with the rpm command. For example: 54</p> 55 56<blockquote> 57<pre> 58$ <b>rpm -qf /usr/lib/libdb.so</b> 59db4-4.3.29-2 60</pre> 61</blockquote> 62 63<p> This means that you need to install db4-devel-4.3.29-2 (on 64some systems, specify "<b>rpm -qf /lib/libdb.so</b>" instead). </p> 65 66<p> DO NOT download some Berkeley DB version from the network. 67Every Postfix program will dump core when it is built with a different 68Berkeley DB version than the version that is used by the system 69library routines. See the DB_README file for further information. 70</p> 71 72<h2>Procmail issues</h2> 73 74<p> On RedHat Linux 7.1 and later <b>procmail</b> no longer has 75permission 76to write the mail spool directory. Workaround: </p> 77 78<blockquote> 79<pre> 80# chmod 1777 /var/spool/mail 81</pre> 82</blockquote> 83 84<h2>Syslogd performance</h2> 85 86<p> LINUX <b>syslogd</b> uses synchronous writes by default. Because 87of this, <b>syslogd</b> can actually use more system resources than 88Postfix. To avoid such badness, disable synchronous mail logfile 89writes by editing /etc/syslog.conf and by prepending a - to the 90logfile name: </p> 91 92<blockquote> 93<pre> 94/etc/syslog.conf: 95 mail.* -/var/log/mail.log 96</pre> 97</blockquote> 98 99<p> Send a "<b>kill -HUP</b>" to the <b>syslogd</b> to make the 100change effective. </p> 101 102</body> 103 104</html> 105
