Topic: Cant establish SMTP connection

[shoaib]

Hi all,

My sme has been running fine since July. But since last couple of days I've been noticing mails to yahoo, hotmail, and gmail stopping in the mail queue and finally coming back to local users with this error:

Sorry,_I_wasn't_able_to_establish_an_SMTP_connection.

I'm in contact with my ISP, but in the meanwhile I want to collect as much information as possible, so as to tackle this problem.

All help would be appreciated.

Thanks

[David Harper]

As a workaround, try using your ISP's mail server to deliver messages, as detailed at http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Chapter13#E-mail_Delivery

Does this help?

[shoaib]

Hi David,
thanks for your suggestion. I'll try it and get back.

[shoaib]

Hi,
I tried the suggested setting, i.e using my isp's smtp server. And the mail slowly started flowing. Now the queue is all empty. But if I stop the relaying, and try to directly use SME's smtp, mails start stopping in queue. Can't understand the problem. This only happens when i try to send mails to international mail servers. I've tested it with a few local mail servers hosted by different ISPs and there is no problem in at all !!!!

qmail current error

starting delivery 64: msg 5147070 to remote xxx@hotmail.com
status: local 0/10 remote 3/20
delivery 64: deferral: Sorry,_I_wasn't_able_to_establish_an_SMTP_connection._(#4.4.1)/

[David Harper]

It's time to file a bug report, I think.

[shoaib]

OK I filed a bugg ! Hope its not a bugg but some config problem !

[janet]

shoaib

But since last couple of days I've been noticing mails to yahoo, hotmail, and gmail stopping in the mail queue and finally coming back to local users with this error:
Sorry,_I_wasn't_able_to_establish_an_SMTP_connection.

More likely a blocking issue with/by those ISP's.

They are refusing a connection with your server as they suspect you of being a spammer.
They use special algorithms to deduce the likelihood of your servers IP being that of a spammer.

You will need to contact those ISP's tech support people to have your servers IP listed on their exclusion list. Have a look on their support websites.
Part of the problem will be that you do not have reverse DNS (PTR) records set up for your domain, you need to get your ISP to do that for you.
Also you need to implement Sender Policy Framework (SPF) records for your domains. Again your ISP is probably the one to do this for you or whoever maintains your DNS records.

Unless you do the above things, don't expect those large ISP's to accept mail from you anymore.

Using your ISP's smtp server to send mail is an easy answer though.

[shoaib]

shoaib

More likely a blocking issue with/by those ISP's.

They are refusing a connection with your server as they suspect you of being a spammer.
They use special algorithms to deduce the likelihood of your servers IP being that of a spammer.

You will need to contact those ISP's tech support people to have your servers IP listed on their exclusion list. Have a look on their support websites.
Part of the problem will be that you do not have reverse DNS (PTR) records set up for your domain, you need to get your ISP to do that for you.
Also you need to implement Sender Policy Framework (SPF) records for your domains. Again your ISP is probably the one to do this for you or whoever maintains your DNS records.

Unless you do the above things, don't expect those large ISP's to accept mail from you anymore.

Using your ISP's smtp server to send mail is an easy answer though.

Hi,
Thanks for the suggestions, but unfortunately your points of concern have been already checked. I've contacted my ISP, to see if my IP or my IP block was in any blacklist, as it often happens. But it was found clean, (checked blacklisting at various sites, including openrbl.org). I have a valid MX record for my IP, a valid reverse DNS, and a valid PTR. Other than that my server strictly denies
relaying. I use webmail or IMAPS for externally accessing mails. MY ISP has given in writing that they are not blocking any ports, neither are they filtering my traffic. So the problem is elsewhere. I hope I can find a solution soon.

[mmccarn]

unfortunately your points of concern have been already checked. I've contacted my ISP, to see if my IP or my IP block was in any blacklist,

You need to check with each email provider to see if they are blocking you.

For example, in the late 90's, AOL would discard email from servers it didn't like
* without generating any error messages
* without providing any mechanism for the sender to find out what happened
* without admitting that it had accepted, then discarded the email from your server.

In this case, you need to contact yahoo, hotmail and gmail to find out why they are blocking SMTP connections from your IP address.  As you have already found out, your ISP may think your IP is fine, but if these email systems won't accept email from you, you still have a problem.

[janet]

shoaib

So the problem is elsewhere. I hope I can find a solution soon.

You have totally misunderstood what I was advising you.

The problem is not with your ISP, and as you deduce the problem is elsewhere.
It is with yahoo, hotmail, and gmail.
They are the ones blocking your sme smtp server from connecting to their smtp server.
The error message clearly says that.
ie
Sorry,_I_wasn't_able_to_establish_an_SMTP_connection.

The blocking is NOT as a result of your sme server IP being on any RBL lists, I never even mentioned those.

As I said, yahoo, hotmail & gmail use special algorithms to deduce the likelihood of your servers IP being that of a spammer.
You will need to contact those ISP's tech support people to have your servers IP listed on their exclusion list. Have a look on their support websites.

OK then, if you have Reverse DNS/PTR records setup then that part is OK.

What about Sender Policy Framework (SPF) records for your domains ?
You will get blocked if you don't have that setup.

I have been through all this, and the ultimate answer is to get your server listed on the exclusion lists maintained by yahoo, hotmail & gmail. But they will not list you until you conform to all their requirements and provide (for example) information about the path your server takes to talk to their servers etc etc and verify that you have put in place certain requirements eg PTR & SPF etc. See their tech support websites for details of the information they want from you.

Search for technical support for system administrators for each of those providers.

[janet]

shoaib

Here's where you start the process going for Hotmail
Look for similar for the other providers

http://postmaster.live.com/

Solutions For:

Senders

Do you send e-mail to Windows Live Hotmail users on a regular basis? Does your organization send e-mail on behalf of other companies (for instance, are you an ISP or ESP)? If you fall into one of these groups and would like to improve the deliverability of your messages to consumers, then read more here.

Here's where you submit your  (detailed) request to Hotmail

https://support.msn.com/eform.aspx?productKey=edfsmsbl&ct=eformts&scrx=1

[shoaib]

Thanks Mary for all your support. I'll start correspondence with hotmail and see where it goes from there, and I assume its a long walk till my server is whitelisted. I'll keep my progress posted.

[pfloor]

shoaib,

Do you have a static or dynamic IP address?

[shoaib]

shoaib,
Do you have a static or dynamic IP address?

Static, paid extra in the package plan to get that.

[akhilmathema]

You can check your IP in one of those sites:
http://www.us.sorbs.net/lookup.shtml

[shoaib]

You can check your IP in one of those sites:
http://www.us.sorbs.net/lookup.shtml

Checked, not listed.

[F650]

I have the same problem.
I could send e-mail to yahoo, hotmail, and mynet but could not receive. Every time i received "Cant establish an SMTP connection" message. I checked my static IP for the blacklist but it was clear. I also checked my server with nmap and port 25 is open. My settings is at  "Allow private and public (secure POP3S)". I could send but could not receive from those services. I have not any experiment on the other services. When i receive the my sme servers messages from yahoo and the others, they did not put me on the junk mail folder or like the spam. I could not understand the problem.    Thanks for your attentions.

[janet]

F650

I have the same problem.
I could send e-mail to yahoo, hotmail, and mynet but could not receive.

Your problem is different to the original poster. OP complains of not being able to send.

Please look at this thread as it may provide some clues and troubleshooting tips.

http://forums.contribs.org/index.php?topic=42355.msg199352#msg199352

[F650]

Thanks for your guide.

[akhilmathema]

Checked, not listed.

try to use your ISP's smtp gateway
# config set SMTPSmartHost your.isp.com

even if doesn't work verify qpsmtpd has public access
# config show qpsmtpd

[shoaib]

try to use your ISP's smtp gateway
# config set SMTPSmartHost your.isp.com

even if doesn't work verify qpsmtpd has public access
# config show qpsmtpd

Yeah I'm doing that (using my ISP's smtp), its working, but my company's policy is against that. Therefore its not a permanent solution. I've written to gmail, yahoo and hotmail. So far none of them has replied ! I guess my last option is to get a new ip from a different ip block.

[janet]

shoaib

I guess my last option is to get a new ip from a different ip block.

That won't necessarily resolve the problems.
Your sending patterns are analysed by hotmail etc, and they use algorithms to decide if you are behaving like a spammer. They are quite agressive too.

Simply sending ten messages in quick succession to different hotmail accounts is enough to get you blocked by them (temporarily usually).

[shoaib]

shoaib

That won't necessarily resolve the problems.
Your sending patterns are analysed by hotmail etc, and they use algorithms to decide if you are behaving like a spammer. They are quite agressive too.

Simply sending ten messages in quick succession to different hotmail accounts is enough to get you blocked by them (temporarily usually).

Then what? Should I change my ISP?? (very difficult task if not impossible)!!!

[janet]

shoaib

Then what? Should I change my ISP?? (very difficult task if not impossible)!!!

I don't understand your attitude of confusion.
You have been given good advice in replies 6, 9, 10 etc and yet you still seem to not understand what the issue is.
Those ISP's are blocking you because of the mail sending pattern your server does.

The way to resolve the issues is to fill in the form at hotmail (& other ISP's tech support pages) eg
https://support.msn.com/eform.aspx?productKey=edfsmsbl&ct=eformts&scrx=1
which will eventually get your server/domain/IP whitelisted at hotmail, then they will acecept lots of emails from you without them being in fear that you are a spammer.

As stated before, you will have to provide many (almost confidential) details to them though, which involve running tests on your server, as per the data being requested in the form fields.

[shoaib]

I've filled and submitted the form which you prescribed earlier, and also wrote a separate email, haven't heard from them yet. No confusion just frustration ! I apologize for my bitter snapping remarks, (no need to bite the helping hand)

[pfloor]

I've filled and submitted the form which you prescribed earlier, and also wrote a separate email, haven't heard from them yet. No confusion just frustration ! I apologize for my bitter snapping remarks, (no need to bite the helping hand)

I'm not going to read this entire thread so if you haven't already done so, you MUST configure an spf record.  It is easy to do if you use DynDNS (and I assume other DNS providers provide a way for you to add an spf record).  This fixed all my problems with hotmail, msn, etc. a long time ago and I never had to contact hotmail.  See this thread, the OP had similar problems with hotmail.

http://forums.contribs.org/index.php?topic=37898.msg170657#msg170657

[janet]

shoaib & pfloor

.. you MUST configure an spf record. 

That was advised to do way back in reply #6, but OP only says:

"I have a valid MX record for my IP, a valid reverse DNS, and a valid PTR."

Part of the confirmation process when working through the form at hotmail is to confirm you have a SPF record. Shoaib you must set one up as pfloor says.