Mail service on, SMTP on, but clients can't connect -- please help a novice

Question

Hi all,
We use 10.4 Server on a G5 Xserve. A few days ago we had a problem with our server being used for spam. That was fixed quickly enough, but the problem is: while being fixed, the mail queue accumulated more and more mail, and it wasn't going out. The "retry" button didn't work. Repairing the database didn't work.
To make a long story shorter, after reading different things here and on the web, I managed to delete all the messages in the queue. All the users are still there. But now, when I turn the mail service back on, everyone gets a "can't connect" error.
I've used the terminal before, but I've always been following directions; I don't know what to type or why. But if someone with patience can help, I can follow directions, and would really appreciate the help. Right now I'm dead in the water.

Answer 1

OK, I've already admitted that I know nothing about this, so I'm sure this will give some people some laughs. That's OK, so the only thing I've changed was the name of the company. I have more peace of mind knowing I'm not showing who's got problems. The other thing is that I don't know when my part of the history begins. Maybe it's all me, but I don't remember doing anything even remotely close to changing IPs. So here it is:
1 telnet mail.abcde.com 110
2 telnet mail.abcde.com 110
3 telnet mail.abcde.com 110
4 sudo /etc/squirrelmail/config/conf.pl
5 grep swupd /etc/swupd/com.apple.server.swupdate.plist > ~/Desktop/
6 update_list.txt
7 grep swupd /etc/swupd/com.apple.server.swupdate.plist > ~/Desktop/
8 update_list.txt
9 grep swupd /etc/swupd/com.apple.server.swupdate.plist > ~/Desktop/update_list.txt
10 softwareupdate
11 man changeip
12 changeip
13 exit
14 changeip -checkhostname
15 sudo changeip
16 changeip -checkhostname
17 sudo changeip -checkhostname
18 man changeip
19 sudo changeip -gethostname
20 sudo changeip -gethostname
21 sudo changeip
22 /usr/sbin/changeip /LDAPv3/127.0.0.1 10.10.10.3 10.10.10.3 mail.abcde.org mail.abcde.org
23 sudo changeip -checkhostname
24 sudo /usr/sbin/changeip /LDAPv3/127.0.0.1 10.10.10.3 10.10.10.3 mail.abcde.org mail.abcde.org
25 changeip -checkhostname
26 sudo changeip -checkhostname
27 sudo rm -rf /usr/share/swupd/html/061-4590/
28 sudo rm -rf /usr/share/swupd/html/061-4589/
29 sudo rm -rf /usr/share/swupd/html/061-4589
30 sudo rm -rf /usr/share/swupd/html/061-4590/
31 sudo rm -rf /usr/share/swupd/html/061-4590/
32 sudo rm -rf /usr/share/swupd/html/061-2089/
33 grep swupd /etc/swupd/com.apple.server.swupdate.plist > ~/Desktop/update_list.txt
34 sudo mkdir /usr/sieve
35 sudo mkdir /usr/sieve
36 sudo pico /etc/services
37 netstat -an | grep 2000
38 telnet localhost 2000
39 sudo mkdir -p /usr/sieve
40 sudo mkdir -p /usr/sieve
41 sudo chown cyrusimap /usr/sieve
42 sudo chgrp wheel /usr/sieve
43 cd
44 pwd
45 ls
46 cd /usr
47 ls
48 ls -l
49 exit
50 sudo pico /etc/services
51 telnet localhost 2000
52 netstat
53 netstat -an | grep 2000
54 exit
55 changeip
56 sudo changeip
57 changeip -checkhostname
58 sudo changeip -checkhostname
59 exit
60 sudo ls -al /var/spool/imap/user/diradmin
61 sudo ls -al /var/spool/imap/user/kbentley
62 sudo /usr/share/mailman/bin/check_perms -f
63 su root
64 su root
65 su root
66 su root
67 su root
68 fsck -f
69 fsck
70 sudo fsck -f
71 sudo fsck /?
72 fsck /help
73 fsck \help
74 pwd
75 ..
76 12345
77 sudo /System/Library/CoreServices/Finder.app/
78 sudo /System/Library/CoreServices/Finder.app/Contents/MacOS/Finder
79 su root
80 su root
81 sudo -u cyrusimap
82 su cyrus
83 su cyrus
84 su cyrus
85 su cyrus
86 su cyrus
87 cyrus
88 sudo cyrus
89 su cyrus
90 su cyrus
91 su cyrus /usr/bin/cyrus/bin/reconstruct -r -f /var/spool/imap/bbills
92 postfix reload
93 sudo postfix reload
94 sudo postfix reload
95 ls -l /var/spool/imap/user/bbills
96 history