Outgoing mail on port 587 AND 25

[zero@]

I have several clients that refuse to use their own ISP's outgoing server because they travel and they don't want to or can't use their ISP's outgoing server. So I did some reading about using port 587 as well as port 25 for outgoing mail. Many ISP's block port 25, but allow port 587.

I thought I could simply redirect requests from port 587 to 25, like so:

iptables -t nat -A PREROUTING -p tcp --dport 587 -i eth0 -j REDIRECT --to-ports 25

That seemed to work fine and allowed me to use both. However, a day or two later it stopped working. I didn't reboot (but someone else might have) or restart any services manually. Is there any wway to make this change permanent?

Also, is there a danger to doing it this way? I'm not 100% fluent with iptables, and I don't want to open myself up to attack.

Running Debian Stable.

Thanks in advance for the help.

 

[105547111]

Okay we need to copy a file and then edit the copy, then restart xinetd..

cd /etc/xinetd.d

cp smtp_psa smtp_additional

(this makes a copy of smtp_psa called smtp_additional)

vi smtp_additional

(so we edit it now)

make the first line say "service submission"

Type :wq! to save your file.


Explanation 'submission' is an alias for port 587.

To make the changes take effect you must restart xinetd


/etc/rc.d/init.d/xinetd restart

That will make qmail (rather, xinetd) respond to smtp requests on port 587 as well as 25.

Cheers

 

[gromett]

Had a client who uses AOL (yuk).
tested this solution with them and it works. It doesn't appear to be affected by plesk updates and is transparent.
Thanks for the solution is is being rolled out over 20 odd servers.

Regards

 

[Mooman2006]

Thanks for posting this solution. I had the same AOL problem and this helped me solve it.

M

 

[NightMan]

We use the port redirect, and it just work fine.

 

[phatPhrog]

Port 587

You can also direct you clients to use the base IP for incoming/outgoing mail in their local client to resolve this issue using port 25.

 

[NightMan]

Re: Port 587

Originally posted by phatPhrog
You can also direct you clients to use the base IP for incoming/outgoing mail in their local client to resolve this issue using port 25.

if your ISP blocking the 3rd party smtp servers,(port 25) then it will not work either domain or IP. so you need to by pass the block by set-up another port, which your clients can use to send mails out.

 

[phatPhrog]

Port testing with 587 and 25

I ran a test using a popular ISP with a local client. Outlook and Outlook Express using port 25 and our server IP as incoming and outgoing mail server instead of the mail.domain.com, etc..

All mail was sent/received without error or delay.

Hope I am not missing the big picture here. We were having problems sending/receiving via our ISP whether using port 587 or port 25 until we changed the in/out to our server IP using port 25. This, of course with a local email client.

We have also noted a decrease in the amount of spam previously received using the mail.domain.com in/out. Don't know if that means anything specific to anyone else, but we are certainly happy about it.

We are using FC4/PSA 8.1.0

 

[NightMan]

Re: Port testing with 587 and 25

Originally posted by phatPhrog
I ran a test using a popular ISP with a local client. Outlook and Outlook Express using port 25 and our server IP as incoming and outgoing mail server instead of the mail.domain.com, etc..

All mail was sent/received without error or delay.

Hope I am not missing the big picture here. We were having problems sending/receiving via our ISP whether using port 587 or port 25 until we changed the in/out to our server IP using port 25. This, of course with a local email client.

We have also noted a decrease in the amount of spam previously received using the mail.domain.com in/out. Don't know if that means anything specific to anyone else, but we are certainly happy about it.

We are using FC4/PSA 8.1.0

Thant seems strange. then your ISP must have been blocking your domain name rather than your IP. changing the IP is worked for you. but I guess the most of the ISP's are blocking the IP's rather than domain names.. And also I do not know how you prevent spam using the IP in the local mail client.. Doesn't make any sense to me.

 

[phatPhrog]

Re: Re: Port testing with 587 and 25

Originally posted by NightMan
.. And also I do not know how you prevent spam using the IP in the local mail client.. Doesn't make any sense to me.

You got me. All I know is my spam via our server, coupled with my local spam/firewall has proven to eliminate a majority of what I was receiving before.

I refer only to my personal experience, not that of my clients.

 

[rkoecchel]

I'd like to employ this same technique only on a freebsd server. Does anyone know the steps I need to take to do so?

 

[amit290]

I upgraded to 8.3.0 and the code inside smtp_additional file got commented out. Probably because of the new mail message submission feature of 8.3.0 . I un-commented them and it now works again.

 

[flasher]

root@server:~ # cd /etc/xinetd.d
bash: cd: /etc/xinetd.d: File or Directory does not exist



Im on Ubuntu 5.0.4

 

[amit290]

Are you sure your typing in

cd /etc/xinetd.d



??

 

[flasher]

You told me. The code you see is the one I typed.

And not founded.