Email Server - Bad list?

[You Need a Thneed]

At work, we hosted our own mail server for several years. At some point, I think some kind of forwarding was allowed (accidentally I think), which seems to have put our domain on some kind of a banned list. For most people, our email works, however, there are specific people, that, for some reason, cannot SEND email to us - it always bounces back to them. I believe that we can send out to anyone.

In the last year, we have switched our email to be controlled by Gmail - still using our old mail domain. The problem still remains.

Any ideas what might of caused this? And more specifically, is there anything we can do to fix the problem?

[Rathji]

I don't see how you being on a black list would cause people not to be able to send email to you, but I am still half asleep right now.

If if you are thinking you are on a blacklist, check out a aggregator and see if that is the case. Verify your DNS settings are correct as well, like spf and txt entries.

[Buff]

That is weird that people can't send to you because you may be blacklisted. When you are blacklisted, you are blocked by spam filters from send spam to certain domains.

Check out this site:
http://www.mxtoolbox.com/blacklists.aspx

It doesn't search CloudMark though and CloudMark has many huge clients. Shaw and Telus use CloudMark as their spam filter.

[photon]

See if you can get a detailed copy of the bounce email they receive.

Could be something really messed up with the DNS entries for the MX records or something.. where most everyone is sending to Google but some for some reason are still trying to send to the old email server, or some other email server.

[Raekwon]

Also it doesn't have to be forwarding, it could be a bad address in the address book that multiple people keep trying to send to. This caused a certain client to pick us up as spam and got us blacklisted.

[You Need a Thneed]

Originally Posted by Raekwon

Also it doesn't have to be forwarding, it could be a bad address in the address book that multiple people keep trying to send to. This caused a certain client to pick us up as spam and got us blacklisted.

the addresses people are sending to is correct, with several of the people sending to us, we've confirmed that they have the correct address, and everyone that has problems sending to us has problems sending to everyone in our company.

[You Need a Thneed]

Originally Posted by Buff

That is weird that people can't send to you because you may be blacklisted. When you are blacklisted, you are blocked by spam filters from send spam to certain domains.

Check out this site:
http://www.mxtoolbox.com/blacklists.aspx

It doesn't search CloudMark though and CloudMark has many huge clients. Shaw and Telus use CloudMark as their spam filter.

Is there a way to check if we are on the cloudmark list?

If it was blacklisted there though, and that meant that everyone using Shaw and Telus couldn't send to us, that would mean a whole lot more people couldn't send to us.

[Rathji]

Originally Posted by You Need a Thneed

the addresses people are sending to is correct, with several of the people sending to us, we've confirmed that they have the correct address, and everyone that has problems sending to us has problems sending to everyone in our company.

Ensure that even though the address they are typing in in correct, that the address in the header they get returned in correct.

There is a bug related to mailto links in Office 2007/10 that will change the email address that you put into the field. Works kind of like this: bob@abc.com is sending an email to Jeff Smith, jeff@xyz.net. Bob's outlook has this bug, and when he sends an email to jeff@xyz.net, it changes the address to <Jeff's Display name>@abc.com, so JeffSmith@abc.com. It can even propagate that change up to the contact in Exchange, if one exists.

[You Need a Thneed]

Originally Posted by photon

See if you can get a detailed copy of the bounce email they receive.

Could be something really messed up with the DNS entries for the MX records or something.. where most everyone is sending to Google but some for some reason are still trying to send to the old email server, or some other email server.

I asked someone whom I know has the problem sending to us, hopefully I can figure out something from that.

[Travis Munroe]

I have a similar situation. I use my domain name email address through gmail and have only come across 2 issues. @scotiabank and @discoverrealestate emails bounce back 100% of the time. I have to change the send from to my gmail address in order for it to go through.

[You Need a Thneed]

Now that our email is served by gmail, is there any way to ask one of the affected people to try to send an email to an IP address?

i.e. sending to myname@123.456.0.1 instead of myname@mycompany.ca?

I know I could do that with our local IP address, but that would be picked up by our local email server (which is still running, but that doesn't get the email where I want it to go).

EDIT: Or would it still work, because our server here might be rerouting mycompany.ca to gmail?

[photon]

Unsure about sending to an IP, but that's what I was talking about with DNS and MX record issues.

You can use this to find out what your MX records are:

http://mxtoolbox.com/SuperTool.aspx?...algarypuck.com

Then you could get one of the users to run this command from a command line inside their network (i.e. the network that their outgoing mail server runs in).

nslookup -type=mx calgarypuck.com

If the IPs jive then something else is going on. Or there's a network issue between their network and Google's mail servers.

If their outgoing mail server is elsewhere than on the same local network as their computers, you'll have to engage their IT support to start investigating.

[photon]

Originally Posted by You Need a Thneed

I asked someone whom I know has the problem sending to us, hopefully I can figure out something from that.

I think that's the best, the bounce message should give you a good idea of what happened.. did it bounce because their server couldn't contact your email server, or did it bounce because your email server rejected it, etc.

[photon]

Originally Posted by You Need a Thneed

EDIT: Or would it still work, because our server here might be rerouting mycompany.ca to gmail?

Maybe but that won't really tell you much about what's actually causing the problem, other than their outgoing email server works (which I presume we already know if they can send email to someone else other than you).

[sclitheroe]

Originally Posted by You Need a Thneed

Now that our email is served by gmail, is there any way to ask one of the affected people to try to send an email to an IP address?

i.e. sending to myname@123.456.0.1 instead of myname@mycompany.ca?

EDIT: Or would it still work, because our server here might be rerouting mycompany.ca to gmail?

This will/should never work on a properly configured system - the SMTP server should only accept inbound for the specific domain its configured for (or should be configured to only explicitly accept mail for the domain its configured for) and furthermore, hosted email means the SMTP server likely handles many domains - it has no idea who the user at an IP address like that is - it could be a recipient behind one of hundreds or thousands of domains.

[sclitheroe]

The users that can't send, is it all users at one or more companies, or some users at one or more companies?

[You Need a Thneed]

Originally Posted by sclitheroe

The users that can't send, is it all users at one or more companies, or some users at one or more companies?

I'm quite sure it's all users at several companies/organizations.

[psicodude]

My guess is that you enabled open relay on your mail server, which is bad. Basically, it allows spammers to use your server to send, well, spam without being an authenticated user. I speak from experience (new Exchange admin....long story).

Many enterprise grade anti-spam devices will block any outgoing or incoming email to any servers with this option enabled. I know for a fact that Proofpoint, Fortinet, and Sonicwall do this by default.

Use this website to check your email server: http://www.spamhelp.org/shopenrelay/