Koozali.org formerly Contribs.org

Mailserver Question

Mailserver Question
« on: February 09, 2008, 01:26:53 PM »
Recently I seem that some e-mail sent from our SME machine don't seem to be getting through.  I don't get any failure message - they're not bouncing back, just getting silently dropped - maybe by spam filtering software? 

Our situation is as follows - the mailserver name is the main company name - for example mycompany.com - but we operate 6 different websites - each under a different virtual site - e.g. product1.com, product2.com etc..  This is because we promote each activity under its own brand name and each brand has a different web site, thus different ibay, and different e-mail addresses - info@product1.com info@product2.com etc. Everything is located one 1 SME 7.3 server with all updates and no added packages/contribs etc.

I've looked at other posts in the forum, and checked using tools at dnsstuff.com, which I found in another post.  One of the things that was flagged by the check of our dns records was that our mailserver identifies itself by a different name to the that shown in the DNS record (mycompany.com instead of product1.com), and that this could maybe be the reason why mails are being dropped.

When I then try to send a mail from info@product1.com, it gets silently dropped, maybe because the message appears to come from mycompany.com instead of product1.com  .  Interestingly, if I reply to a e-mail sent to info@product1.com, some replies get through, some don't.  To bigger companies (who maybe have more sophisticated protection?), they mostly don't get through.

As far as I can tell, the name by which the mailserver identifies itself when it tries to send mail is the name which is created using the initial setup panels when installing the server.  Is there any way to change the name so that the mailserver identifies itself correctly for each of the virtual domains hosted on the site?

I would be interested to know if any forum users have similar experience, or if you think that there could be another reason for my problem.

Offline raem

  • *
  • 3,972
Re: Mailserver Question
« Reply #1 on: February 09, 2008, 02:14:20 PM »
dave simmons

Lots of mail servers are now using various methods to block email, they are sometimes a bit heavy handed too.
Here is a workaround that may be sufficient to resolve your problems.
If not already the case, add your ISP's mail server in the server manager Email panel in "Address of Internet provider's mail server" eg mail.yourisp.com

If this fixes it great, but perhaps more tweaking of DNS records will be needed, and/or you will need to request whitelisting of your server by other mail servers.
...

Re: Mailserver Question
« Reply #2 on: February 09, 2008, 02:35:34 PM »
Hi Ray,

Thanks for your reply.  Unfortunately I don't think that your first suggestion is an option for us - maybe for people using SME on a DSL line with variable IP address.  We've got a portion of a class C address and the provider expects us to be able to sort everything out ourselves - which we mostly can do.

Regarding whitelisting (I know this can solve the problem because I succeeded with one company in England last week) - how can I do it?  To give an example - we recently acquired a new Cisco router - I registered with Cisco via the web page, and then had to send an e-mail to get access to more downloads which are only available for customers - no response.  A company like Cisco is probably a big target for hackers and other baddies, so it's no surprise that they have good protection.  If I can't e-mail them, how can I contact them to get whitelisted?  Telephoning would be quite difficult (time difference) and expensive.  Plus wherever you call theses days, especially in big companies, you never get anyone on the line who knows or can do anything  Fax?  Also, who is going to listen?  We are only a small company.

Also, if I have to do this a lot, I won't have any time to do my proper job.

Spam - and therefore spam protection - is a fact, and it will probably get worse before it gets better.  If (one of) the reasons that mail gets rejected is because of this machine name issue, this could have a big effect on the use of not only SME, but other distributions which enable mutiple domains to be hosted on one machine.

I have checked our DNS settings - everything seems OK.  Our IP addresses are not listed at Spamhaus or anywhere else as far as I can see.  None of the domain names are blacklisted anywhere as far as I can tell. 

All I really need to know is why our mail doesn't get through.  It may be that the machine name isn't the only problem.

Maybe I should add - we don't do any bulk mailing - all our mails are either to customers/prospective customers, and we only collect e-mail addresses via our web sites and trade shows etc. We are very careful here with our PC's - good antivirus etc. - and have never had an infected PC send out spam mails - so nobody should want to block us.
« Last Edit: February 09, 2008, 02:41:06 PM by dave simmons »

Offline raem

  • *
  • 3,972
Re: Mailserver Question
« Reply #3 on: February 09, 2008, 03:11:43 PM »
dave simmons

I have a static IP and use my ISP's mail server. It saves a lot of hassles of the type you are mentioning.

On other servers with a static IP where the mail server talks directly to the Internet, you may/will need to put reverse DNS lookup entries for each domain.
Also many mail servers eg hotmail are now requiring Sender Policy Framework/Sender ID (SPF) entries in the DNS records for each domain.
Also for companies who do greylisting eg yahoo, you need to contact them directly to get your servers IP whitelisted.

Note that where you use your ISP's mail server, you may/will also need to get them to add a reverse DNS lookup record for you.

There is no one answer for all situations.

As far as why this is happening to you, you need to analyse your email messages, contact those mail server sysadmins who are blocking you and find out why, or log on to their websites and search the tech support pages. I can't tell you specifically why, but I have suggested the most likely causes currently going around.

Telephoning overseas is very cheap if you use a VOIP service eg SkypeOut etc at 1.8 cents per minute.

I also do not send bulk mail and keep my server very well protected, but many companies are rather gung ho with blocking and greylisting/blacklisting for no apparent reason. You can only follow through on each instance and get yourself unblocked.
I do not see this as a issue particular to sme server, it's an issue to do with how reactive other sysadmins make their mail servers, and how your DNS records are configured. As mail systems get tougher/tighter then we need to react correspondingly and make any required changes to keep our systems running smoothly.

« Last Edit: February 09, 2008, 03:31:18 PM by RayMitchell »
...

Re: Mailserver Question
« Reply #4 on: February 09, 2008, 03:48:06 PM »
Hi Ray,

Thanks again.  I agree that it's not a problem that is necessarily unique to SME, but this is about the best forum I know to get answers to my questions.

I have a few follow-up questions if that's OK.

I'll have to contact my ISP to see if I have access to their mail servers.  I don't see any mention of it in our contract or on their website help section.  That'll be something for next week.

I see that you have a static IP.  Do you do your own DNS?  (We do)  The reason I ask is that setting up correct reverse DNS seems not to be possible if you (like us) have only a portion of a Class C address, and want to maintain your own DNS records.  The reason we do our own is because we have our domain names with a different registrar to our ISP.  Our ISP is relatively expensive for domain name registration (nearly 8 times what we currently pay), and won't do our DNS unless we register our domain names using their service. 

This hasn't been a problem in the past (I mean reverse DNS).  I have searched the net over reverse DNS and it seems that I need a full Class C address to do correct reverse DNS myself.  As I don't have access to nuclear weapons (or large amounts of cash) my chance of getting a full Class C address is nil. I have contacted the ISP about reverse DNS because I read somewhere on the web that it WAS possible to subdivide Class C for reverse DNS, so long as the ISP played along.  I contacted my ISP and got the anwser - 'Yes, we've also had that request from other customers, and we could do it, but we're not going to'. 

We don't currently have SPF records in our DNS.  I've only recently become aware of SPF (I'm not a computer 'techie') and maybe this would be enough to solve the problem.  Can you point me in the direction of good information over how to set this up?

I know this is no longer SME territory, but if you or anyone else knows if it is possible to do reverse DNS (without the co-operation of the ISP) for only a section of a Class C address, please let me know.

What we really need to do is make the world more aware of SME.  Mail filtering works just fine for us - I see in the logs that loads of mails are stopped - mostly by the blacklist system, and some than by Spamassassin - and all the right ones get through!  All this and I don't even have to have any technical knowledge.  SME is really a brilliant system.  If everyone uses it we won't have this problem! :-)

I would also like to thank you Ray for your replies.  I regularly search the forum for help and you always seem to give quick and very helpful advice to people who post.

Offline raem

  • *
  • 3,972
Re: Mailserver Question
« Reply #5 on: February 09, 2008, 04:01:19 PM »
dave simmons

I don't know about your Class C address issues, someone else will have to answer that.

As far as I know you need to contact your ISP or DNS record maintainer to have reverse DNS (PTR) records & SPF records setup.

If you are "doing DNS yourself" then you obviously need to learn how.

Google is your friend, as Charlie always says.

The requirement for reverse DNS & SPF records has become a problem in recent times due to stricter controls being applied by mail servers, due to spam etc.

I could only suggest, change your ISP to someone who is more co-operative.

You can also block a lot of legitimate email from getting to your sme server if you are over zealous with RBL list configuration, and that is basically one of the things that external ISP's mail servers are doing ie being over zealous.
...

Re: Mailserver Question
« Reply #6 on: February 09, 2008, 05:53:58 PM »
Ray,

Have set up the SPF records.  As you say, Google is my friend!

Will wait a couple of days for the records to propagate, and see if it makes a difference.

Thanks again.