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-   -   Beating my head against the email wall - cannot receive email (https://www.linuxquestions.org/questions/linux-server-73/beating-my-head-against-the-email-wall-cannot-receive-email-666761/)

dazed-and-confused 08-31-2008 11:16 PM
Beating my head against the email wall - cannot receive email
 
Greetings -

I'm killing myself trying to figure out how to receive email to my server. I can send email all day without any problems, but am yet to receive a single email not sent locally.

I'm using exim4 to send, mutt to read. What else do I need to do? I'm really at a loss.

MX record via dig:
Code:
dazed@duff:~$ dig mx grimdar.com

; <<>> DiG 9.3.4-P1.1 <<>> mx grimdar.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31457
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;grimdar.com.                  IN      MX

;; ANSWER SECTION:
grimdar.com.            86400  IN      MX      50 mail.grimdar.com.

;; Query time: 39 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Mon Sep  1 00:10:55 2008
;; MSG SIZE  rcvd: 50
Now with regard to mail.grimdar.com, there is no box named that. Don't know if that is important or not, like I said I'm really at a loss here and have found nothing helpful (that I recognize as helpful anyway) as far as just how an MX record should look and what all the parts of such a record relate to.

What other information can I supply you with? Any help is sincerely appreciated.

chort 08-31-2008 11:41 PM
Code:
[chort@horus4 chort]$ dig +short mail.grimdar.com
68.57.212.10
[chort@horus4 chort]$ telnet mail.grimdar.com 25
Trying 68.57.212.10...
telnet: connect to address 68.57.212.10: Operation timed out
telnet: Unable to connect to remote host
Port 25/tcp is blocked.

Matir 09-01-2008 01:00 AM
If there is no mail.grimdar.com box, where do you expect incoming mail to come to? The MX record is what all remote servers use to look up the mailservers handling delivery for grimdar.com. If you want to point mail to, say, server1.grimdar.com, change the MX record to reflect that.

dazed-and-confused 09-01-2008 06:38 AM
Quote:
Originally Posted by Matir (Post 3265778)
If there is no mail.grimdar.com box, where do you expect incoming mail to come to? The MX record is what all remote servers use to look up the mailservers handling delivery for grimdar.com. If you want to point mail to, say, server1.grimdar.com, change the MX record to reflect that.
Ok, thanks. I did change the record now to point to duff.grimdar.com, which is a legit target. I shot an email to rolf@grimdar.com after making the change but it never arrived (or hasn't arrived after twenty minutes, and i do not believe it will arrive). See my next reply about port 25 if that's any help. I continue to be at my wit's end over this issue.

dazed-and-confused 09-01-2008 06:44 AM
Quote:
Originally Posted by chort (Post 3265734)
Code:
[chort@horus4 chort]$ dig +short mail.grimdar.com
68.57.212.10
[chort@horus4 chort]$ telnet mail.grimdar.com 25
Trying 68.57.212.10...
telnet: connect to address 68.57.212.10: Operation timed out
telnet: Unable to connect to remote host
Port 25/tcp is blocked.
Right I did change the MX record to point to duff.grimdar.com, but my remote telnet session still gives the same time out. Below is a dump of my results. Can you educate me on why port 25 being blocked or inaccessible is impacting my mail receipt? I thought mail went outbound on 25 and inbound on 110? Or is that just pop3 mail and does not apply in my setup?
Code:
rolf@asgard:~$ telnet duff.grimdar.com 25
telnet: could not resolve duff.grimdar.com/25: Name or service not known
rolf@asgard:~$ telnet grimdar.com 25
telnet: could not resolve grimdar.com/25: Name or service not known
rolf@asgard:~$ telnet www.grimdar.com 25
Trying 68.57.212.10...
telnet: connect to address 68.57.212.10: Operation timed out
telnet: Unable to connect to remote host

dazed-and-confused 09-01-2008 06:52 AM
For more information, I hope, here is a tail of my /var/log/exim4/mainlog - which has really never shown any errors. I sent out a test email from duff.grimdar.com to my comcast.net email, which worked as expected and has always worked.
Code:
2008-09-01 06:24:15 End queue run: pid=5170
2008-09-01 07:24:15 Start queue run: pid=5806
2008-09-01 07:24:15 End queue run: pid=5806
2008-09-01 07:32:20 1Ka7ds-0001W9-9i <= rolf@grimdar.com U=rolf P=local S=478 id=20080901113220.GA5829@duff.grimdar.com
2008-09-01 07:32:21 1Ka7ds-0001W9-9i => rolf@comcast.net R=smarthost T=remote_smtp_smarthost H=smtp.g.comcast.net [76.96.62.117] X=TLS-1.0:RSA_AES_256_CBC_SHA1:32 DN="C=US,ST=Pennsylvania,L=Philadelphia,O=Comcast Cable Communications Management LLC,OU=Business Center,CN=smtp.comcast.net"
2008-09-01 07:32:21 1Ka7ds-0001W9-9i Completed

ledow 09-01-2008 07:05 AM
duff.grimdar.com doesn't resolve to an IP address at all for me. And
http://www.mxtoolbox.com tells me that it isn't just me that can't resolve duff.grimdar.com! mail.grimdar.com did resolve - it's just that it's port was blocked.

The MX record should point (eventually) to a valid, globally resolveable name from which an IP address can be obtained from every DNS server in the world. The computer at that IP address needs port 25 open and to have mail server software running. You haven't got the first step working.

ledow 09-01-2008 07:08 AM
Quote:
Originally Posted by dazed-and-confused (Post 3266022)
I sent out a test email from duff.grimdar.com to my comcast.net email, which worked as expected and has always worked.
Sending is completely different to receiving. You need almost NOTHING to send an email correctly (although it's more likely to get spam-filtered without being from a valid domain etc.).

All that log says is that it sent an email to Comcast. That's got nothing to do with you recieving email addressed to @yourdomain.com

dazed-and-confused 09-01-2008 07:19 AM
Quote:
Originally Posted by ledow (Post 3266032)
duff.grimdar.com doesn't resolve to an IP address at all for me. And
http://www.mxtoolbox.com tells me that it isn't just me that can't resolve duff.grimdar.com! mail.grimdar.com did resolve - it's just that it's port was blocked.
ledow, thanks for the reply. Maybe since I just updated the MX record the changes need time to disperse? I don't know why else duff.grimdar.com would not resolve.

Quote:
The MX record should point (eventually) to a valid, globally resolveable name from which an IP address can be obtained from every DNS server in the world. The computer at that IP address needs port 25 open and to have mail server software running. You haven't got the first step working.
Ok, I went out to joker.com and looked at my A record - no entry for duff.grimdar.com, so I added one. Now the record looks like this:
Code:
Host                                  Target                     
duff.grimdar.com                68.57.212.10
www.grimdar.com                        68.57.212.10
mail.grimdar.com                68.57.212.10

MX-Records
Priority          Mail server (from)        Target mail server (to)                   
50                        grimdar.com                duff.grimdar.com

dazed-and-confused 09-01-2008 07:21 AM
Quote:
Originally Posted by ledow (Post 3266035)
Sending is completely different to receiving. You need almost NOTHING to send an email correctly (although it's more likely to get spam-filtered without being from a valid domain etc.).

All that log says is that it sent an email to Comcast. That's got nothing to do with you recieving email addressed to @yourdomain.com
I agree with you, but do not know where to start to be able to receive emails sent to the grimdar.com domain. What common "things" can I check or modify to get this working?

Matir 09-01-2008 11:37 AM
In order to receive mail, the following conditions (among others) must be true:
  1. You must have a valid MX record for the domain.
  2. The MX record must point to a host with a valid A record.
  3. The host must be running a mailserver.
  4. Port 25 (SMTP) must not be firewalled and must be able to receive connections.

Right now, I can resolve duff.grimdar.com, but not connect to port 25. It appears that host is using Comcast for an ISP. I would check and see if Comcast is blocking connections to port 25. If it is a residential connection, I would strongly suspect this to be the case.

checkmate3001 09-01-2008 11:53 AM
I have comcast - and to my knowledge they haven't been blocking port 25 (although I wouldn't doubt it... it is comcast). You prolly have already done this, but make sure your router forwards port 25 to your machine. Make sure any firewall on your machine is allowing port 25 to be open.

dazed-and-confused 09-01-2008 06:59 PM
Quote:
Originally Posted by Matir (Post 3266249)
In order to receive mail, the following conditions (among others) must be true:
  1. You must have a valid MX record for the domain.
  2. The MX record must point to a host with a valid A record.
  3. The host must be running a mailserver.
  4. Port 25 (SMTP) must not be firewalled and must be able to receive connections.

Right now, I can resolve duff.grimdar.com, but not connect to port 25. It appears that host is using Comcast for an ISP. I would check and see if Comcast is blocking connections to port 25. If it is a residential connection, I would strongly suspect this to be the case.
Comcast is the ISP, and I believe they are blocking all port 25 traffic. Is there a way around this bloackage on my end? I will contact comcast and ask them to allow me unfettered access to port 25, but I anticipate they will ignore me.

dazed-and-confused 09-01-2008 07:01 PM
Quote:
Originally Posted by checkmate3001 (Post 3266271)
I have comcast - and to my knowledge they haven't been blocking port 25 (although I wouldn't doubt it... it is comcast). You prolly have already done this, but make sure your router forwards port 25 to your machine. Make sure any firewall on your machine is allowing port 25 to be open.
Right, I have set this box outside the firewall - it is totally exposed to the big scary internet. All ports should be open, but to make sure I did specify in my router settings to forward port 25 traffic to that box.

Are you as a comcast user able to telnet to port 25 from outside your domain? I am not.

dazed-and-confused 09-01-2008 07:13 PM
Quote:
Originally Posted by Matir (Post 3266249)
  • You must have a valid MX record for the domain.
I think it's valid. As far as I can tell, it is valid.

Quote:
  • The MX record must point to a host with a valid A record.
I think it's valid. As far as I can tell, it is valid.

Quote:
  • The host must be running a mailserver.
Check - exim4, which can send mail all day, is working fine. Does exim4 receive mail? If not, what do you recommend for mail receiving purposes??

Quote:
  • Port 25 (SMTP) must not be firewalled and must be able to receive connections.
Definitely not firewalled, but apparently unable to receive connections.


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