Change SMTP port

[travisbrown]

How can I change the SMTP port on a W2K3 server to something other than 25? We changed ISPs at our office and the new providers have blocked 25. Now all apps using CDO fail.

Thanks

 

[AckeyG]

It just doesn't make sense, since it will not work.

Answer: Even if we will enable that option, if you choose a different port, other than 25, nobody will be able to receive your emails, because all SMTP hosts and servers work on port 25 which is a standard for SMTP as defined by Internet Engineering Task Force(IETF). You can specify port in your email program, but that is only when your own SMTP Server is configured to receive connections on port other than 25. But from your SMTP to the destination SMTP, I can pretty much assure you it goes on the port 25, other programs take other ports. Here is just a partial services file that shows you how different programs use different ports as standard.

echo 7/tcp
echo 7/udp
discard 9/tcp sink null
discard 9/udp sink null
systat 11/tcp users #Active users
systat 11/tcp users #Active users
daytime 13/tcp
daytime 13/udp
qotd 17/tcp quote #Quote of the day
qotd 17/udp quote #Quote of the day
chargen 19/tcp ttytst source #Character generator
chargen 19/udp ttytst source #Character generator
ftp-data 20/tcp #FTP, data
ftp 21/tcp #FTP. control
telnet 23/tcp
smtp 25/tcp mail #Simple Mail Transfer
time 37/tcp timserver
time 37/udp timserver
rlp 39/udp resource #Resource Location
nameserver 42/tcp name #Host Name Server
nameserver 42/udp name #Host Name Server
nicname 43/tcp whois
domain 53/tcp #Domain Name Server
domain 53/udp #Domain Name Server
bootps 67/udp dhcps #Bootstrap Protocol Server
bootpc 68/udp dhcpc #Bootstrap Protocol Client
tftp 69/udp #Trivial File Transfer
gopher 70/tcp
finger 79/tcp
http 80/tcp

http://www www-http

#World Wide Web
kerberos 88/tcp krb5 kerberos-sec #Kerberos
kerberos 88/udp krb5 kerberos-sec #Kerberos
hostname 101/tcp hostnames #NIC Host Name Server
iso-tsap 102/tcp #ISO-TSAP Class 0
rtelnet 107/tcp #Remote Telnet Service
pop2 109/tcp postoffice #Post Office Protocol - Version 2
pop3 110/tcp #Post Office Protocol - Version 3
sunrpc 111/tcp rpcbind portmap #SUN Remote Procedure Call
sunrpc 111/udp rpcbind portmap #SUN Remote Procedure Call
auth 113/tcp ident tap #Identification Protocol
uucp-path 117/tcp
nntp 119/tcp usenet #Network News Transfer Protocol
ntp 123/udp #Network Time Protocol
epmap 135/tcp loc-srv #DCE endpoint resolution
epmap 135/udp loc-srv #DCE endpoint resolution
netbios-ns 137/tcp nbname #NETBIOS Name Service
netbios-ns 137/udp nbname #NETBIOS Name Service
netbios-dgm 138/udp nbdatagram #NETBIOS Datagram Service
netbios-ssn 139/tcp nbsession #NETBIOS Session Service
imap 143/tcp imap4 #Internet Message Access Protocol
pcmail-srv 158/tcp #PCMail Server
snmp 161/udp #SNMP
snmptrap 162/udp snmp-trap #SNMP trap

 

[travisbrown]

Yeah, I've got that. The applications email specific and dedicated addresses - notifications and the like. If we change the listening port for that domain on the SMTP server to match, it should work, shouldn't it?

 

[AckeyG]

Would it not be easier for the provider to unblock the port, or go into the router of your ISP and do a port forward to another port which will match on the server?

 

[travisbrown]

It's just standard telcom business ADSL line. They want an additional $1200 per year to upgrade to a package with port 25 open. Infortunately, it's the only ISP who services the building my office is in.

I just thought it would be an easy thing to change the ports. No worries. I'll figure something out.