Dabosa
asked on
ISP block port 25 - VPN client option?
Hi
Im using EAsendmail in a vb.net app to send emails.
It works on in my office VPN. But testing from my broadband at home my ISP blocks port 25 and I cannot send.
Using then the VPN cisco client over my broadband I wthought this would work but i can still not IE telnet to our inbount SMTP, probably because my broadband determines the external route,.
Is there any way I can solve this with the VPN client?
Thanks
Dab
Im using EAsendmail in a vb.net app to send emails.
It works on in my office VPN. But testing from my broadband at home my ISP blocks port 25 and I cannot send.
Using then the VPN cisco client over my broadband I wthought this would work but i can still not IE telnet to our inbount SMTP, probably because my broadband determines the external route,.
Is there any way I can solve this with the VPN client?
Thanks
Dab
Consider using the Message Submission protocol port on port 587 to get around port 25 blocks. Also you might want to verify the route to your smtp server over your vpn client (e.g. tracert <hostname>) to verify you are reaching the internal (office side) address of your SMTP server and not the external interface. Your PIX administrator may have also blocked VPN clients from using port 25.
ASKER
Ok but if it turns out the internal smtp is not reached, if this were to be fixed should it work on port 25 eventhough My isp is blocking it? considering VPN client is not blocking.
If you did a traceroute and the ICMP packets reached the server you are trying to get to then chances are your PIX is set to block port 25 traffic from VPN clients.
ASKER
I only know the external ip of smtp inbound, hos can i determine the internal interface?
Traceroute to external is unreachable. The app uses dns lookup also and is automatically going to the external adress.
Traceroute to external is unreachable. The app uses dns lookup also and is automatically going to the external adress.
ASKER
It uses dnslookup to send the email
ASKER
It works on another isp that is not blocking 25 and this is when connecting with or without the VPN client
Can you send any other IPsec traffic at all? I assume you use IPsec VPN.
ASKER
yes everything else is working with vpn clinet, outlook2007 for instance my servershares ect- all i want is to make the app (EASENDMAIL) think im in the office when im on vpnclient at home. the app uses dnslookup checks the mx record and sends using port 25. My ISP block port 25.
so If I telnet to port 25 its not working when on vpn client. This is what I need to work, like @ the office, can it be done?
so If I telnet to port 25 its not working when on vpn client. This is what I need to work, like @ the office, can it be done?
I see. Just was wondering. Sounds stupid to block SMTP port. How do you know your ISP blocks this port vs. some other device/firewall? Did you contact/ask them? Somehow this does not make sense to me.
When you do a manual DNS lookup on your mail server name configured in your mail app does it resolve to a public (external) IP or your internal (private) IP? I am wondering if it's a Split DNS issue.
When you do a manual DNS lookup on your mail server name configured in your mail app does it resolve to a public (external) IP or your internal (private) IP? I am wondering if it's a Split DNS issue.
ASKER
Not really stupid as this diminishes spam on ISP's network, but very sad for me who wants to use it.
if I do dnslookup for MX to our domain it resloves to the external smtp. I just can send anything because of the port block.
if I do dnslookup for MX to our domain it resloves to the external smtp. I just can send anything because of the port block.
ASKER
I know they block because its on their site and if I test for example:
the 4 largest ISP's in Sweden seem to block it also.
telnet smtp.gmail.com 25
I get no respons
the 4 largest ISP's in Sweden seem to block it also.
telnet smtp.gmail.com 25
I get no respons
ASKER
Ive tested Telia, Telenor and BBB (bredbandbolaget)
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As I said your DNS resolution needs to be split.
ASKER
Its the solution