Hello,
If your users are complaining that they are not able to send mails, a case where their internet is working, but when they try sending mail from their email client like outlook, outlook express, thunderbird, eudora, etc. and in their mail client they are getting an error like ‘not able to connect to the smtp on the server ….’
you may find that when you configure their email account , you may be able to send mails , but they are not, their email client is not even able to connect to your smtp server, and ehn you check , you may find that you are even able to telnet to your port 25 and 110
You may think that it may be the ISP’s issue at the customer’s end.
But its not the same always.
This time we figured outthat the relayd on exim was not working, we asked the user for their public ip address.
and entered the ip address in
# /etc/relayhosts
# /etc/relayhostsusers
then restart the exim.
This helped us, the issue was solved, the user was able to send mails 
In Exim if you are receiving this error
“Spool file is locked (another process is handling this message)”
There could be many reasons to it,
it may be due to the DNS, or firewall,etc.
We had also faced the same error. and this is how we solved it.
#cd /var/spool/exim4/db
# mv * /backup
(moved all the files to a backup folder)
#/etc/init.d/exim4 restart
And it did the trick,
exim worked, hope it may be useful to you too.
# cd /etc/stunnel
[replace 'domain' with your domain]
# openssl req -newkey rsa:1024 -keyout
mail.domain.com.tmp.pem -nodes -x509 -days 9999 -out mail.domain.com.tmp2.pem
# cat mail.domain.com.tmp.pem > mail.domain.com.pem && echo “” >>
mail.domain.com.pem && cat mail.domain.com.tmp2.pem >> mail.domain.com.pem
vi /etc/stunnel/stunnel.conf
# stunnel configuration file
# Copyright by Martin Vernooij – 2005
cert = /etc/stunnel/mail.domain.com.pem
chroot = /var/run/stunnel
pid = /stunnel.pid
setuid = nobody
setgid = nobody
# Workaround for Eudora bug
options = DONT_INSERT_EMPTY_FRAGMENTS
# Some debugging stuff
debug = 3
output = /var/log/stunnel.log
# Some performance tunings
socket = l:TCP_NODELAY=1
socket = r:TCP_NODELAY=1
# Service-level configuration
[pop3s]
accept = 38.99.248.82:995
connect = 110
[imaps]
accept = 38.99.248.82:993
connect = 143
[smtps]
accept = 38.99.248.82:465
connect = 25
# mkdir /var/run/stunnel
# chown nobody:nobody /var/run/stunnel
# stunnel /etc/stunnel/stunnel.conf
# vi /etc/rc.d/rc.local
add this line
stunnel /etc/stunnel/stunnel.conf
