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hans51's Avatar
Posts: 25 | Thanked: 5 times | Joined on May 2010 @ Philippines and Cambodia
#1
In the Philippines the largest mobile ISP/mobile network Smart - blocks port 25, thus making sending of eMail from the N900 impossible via my own mail-server.

For my laptop connections I bypass this port 25 block successfully by port forwarding in bash:

ssh -L 44999:localhost:25 root@xxx.xxx.xxx.xxx
and the mail client thus has an smtp server
localhost:44999

is there a way to use port forwarding for eMail on a N900 and is there a localhost MTA on a N900 to accept and forward such mails ??

of course there might be third party mail accounts
BUT I have a strict SPF record set for my mail servers to ONLY have my own clean IP addresses as used sender IPs. I love to keep my SPF record that strict.

Any help apreciated
 
Posts: 131 | Thanked: 62 times | Joined on Feb 2010
#2
Originally Posted by hans51 View Post
In the Philippines the largest mobile ISP/mobile network Smart - blocks port 25, thus making sending of eMail from the N900 impossible via my own mail-server.

For my laptop connections I bypass this port 25 block successfully by port forwarding in bash:

ssh -L 44999:localhost:25 root@xxx.xxx.xxx.xxx
and the mail client thus has an smtp server
localhost:44999

is there a way to use port forwarding for eMail on a N900 and is there a localhost MTA on a N900 to accept and forward such mails ??

of course there might be third party mail accounts
BUT I have a strict SPF record set for my mail servers to ONLY have my own clean IP addresses as used sender IPs. I love to keep my SPF record that strict.

Any help apreciated
Hi

Use OpenVPN to create a tunnel between the N900 and your SMTP server on any port you choose to forward through your home router.

Then you can use local addressing and port 25 as you like over the tunnel.

This has the added advantage of not exposing your mail server to potentially erroneous mail relay configuration issues.

rgds
 
Posts: 247 | Thanked: 91 times | Joined on Jan 2008 @ London/M4 Corridor
#3
Originally Posted by hans51 View Post
In the Philippines the largest mobile ISP/mobile network Smart - blocks port 25, thus making sending of eMail from the N900 impossible via my own mail-server.
Do they also block the SSL or TLS encrypted ports for SMTP? You may be able to configure your email server to accept thos connections (if it doesn't already) and then have the N900 connect there.
__________________
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If you don't know who the Eletronic Frontier
Foundation are, you should. Check out
http://www.eff.org.
 
Posts: 5 | Thanked: 1 time | Joined on Jan 2010
#4
There's also a tool called "portfwd" (which does precisely what it says...) - check here : http://portfwd.sourceforge.net/

Originally Posted by hans51 View Post
In the Philippines the largest mobile ISP/mobile network Smart - blocks port 25, thus making sending of eMail from the N900 impossible via my own mail-server.

For my laptop connections I bypass this port 25 block successfully by port forwarding in bash:

ssh -L 44999:localhost:25 root@xxx.xxx.xxx.xxx
and the mail client thus has an smtp server
localhost:44999

is there a way to use port forwarding for eMail on a N900 and is there a localhost MTA on a N900 to accept and forward such mails ??

of course there might be third party mail accounts
BUT I have a strict SPF record set for my mail servers to ONLY have my own clean IP addresses as used sender IPs. I love to keep my SPF record that strict.

Any help apreciated
 
breakd0wn's Avatar
Posts: 96 | Thanked: 35 times | Joined on May 2010
#5
Just configure your mail server to listen on an additional port.
 
hans51's Avatar
Posts: 25 | Thanked: 5 times | Joined on May 2010 @ Philippines and Cambodia
#6
the built in mail client does apparently NOT allow
localhost
as mail server
which makes a common portforwarding mail server for outgoing mail like in my laptop ...

localhost:44999
impossible so far

maybe I need to install additional packages to enable localhost as valid email server ??
 
hans51's Avatar
Posts: 25 | Thanked: 5 times | Joined on May 2010 @ Philippines and Cambodia
#7
Hi guys
thanks for the help so far
but

1.
the portforwarding part is NO problem - it works with above line on the N900 as it works on my laptop

the remaining problem is getting mail OUT

localhost may have NO mail agent to handle mail locally for forwarding

2.
I tried repeatedly to change various ports on my mail server
among others also rfc alternate port 587
and a few others

i walked through a complete telnet smtp session on my laptop successfully using alternate port

but on my N900 it seems that the provider blocks just anything related to outgoing mail independent of port
on the mail server there are NO error message at all when attempting to send mail from N900

and of course the receiving of mail works perfectly from N900

personally when comparing alternate port to portforwarding using a secure tunnel. I prefer ssh portforwarding as in my laptop to ensure nothing is sent clear text.

so maybe I have to install postfix or something comparable on my N900 to send locally and use pfwd ?
anyone experience in such procedure with N900 ?
 
Posts: 131 | Thanked: 62 times | Joined on Feb 2010
#8
Once again may I suggest having a look at OpenVPN.

Once you have a tunnel through to your mailserver on any port you choose so it should not get blocked by your ISP.

You will have access to the local IP address of the mail server (the other end of the tunnel).

you can then use

mailserver.vpntunnel.ip.address:25

from the N900

All you need then is to tell the mailserver to allow relay from the vpn tunnel address range.

rgds
 
Posts: 543 | Thanked: 181 times | Joined on Aug 2009 @ Universe,LocalCluster.MilkyWay.Sol.Earth.Europe.Slovenia.Ljubljana
#9
Try using telnet on the n900 and walk through the smtp session that way.
__________________
For any repos or anything else I might have working on my N900 see:
http://wiki.maemo.org/User:Ruskie
A quick list of what I have in the repos
zsh|xmms2|fcron|gtar|gcoreutils
 
Posts: 131 | Thanked: 62 times | Joined on Feb 2010
#10
Originally Posted by ruskie View Post
Try using telnet on the n900 and walk through the smtp session that way.
But that will only confirm to him whether port 25 is open or not.

instructions

telnet ipaddress 25
EHLO

should elicit a response from the mail server.

rgds
 
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