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Outlook Cannot Send Messages Suddenly

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28 comments

  • cPRex Jurassic Moderator
    Hey there! I'm sorry to hear about the issue with Outlook. Do you have root access to the server? Many providers are limiting access to port 25 on their networks, so it's possible there was a network change causing this problem. A quick way to test this would be to perform a "telnet" test from one of the affected computers to the server to see if that port is open. First, you'll want to make sure telnet is enabled on your machine by following the details here:
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  • PostAlmostAnything
    I have root access, but I don't use port 25 because Century Link won't allow outbound connections on that port.
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  • cPRex Jurassic Moderator
    Can you try the test with the current port you're using? That may be 26 or some other alternate port. It's also important to note that we don't provide your hosting - we do create the cPanel software that your hosting provider users, but we have no control over your personal server or hosting environment.
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  • sparek-3
    What specific settings are you using in your Outlook? If you're connecting securely either through tls_on_connect or TLS upgrade - has the secure certificate for the used hostname expired? Do you have cPanel automatic updates enabled? No real clue if cPanel recently pushed out any updates, the cPanel folks here would have a better idea of that. Do you have automatic OS updates enabled? Perhaps an update to OpenSSL or Dovecot happened that you were unaware of.
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  • PostAlmostAnything
    I use port
    Hey there! I'm sorry to hear about the issue with Outlook. Do you have root access to the server? Many providers are limiting access to port 25 on their networks, so it's possible there was a network change causing this problem. A quick way to test this would be to perform a "telnet" test from one of the affected computers to the server to see if that port is open. First, you'll want to make sure telnet is enabled on your machine by following the details here:
    When trying to run telnet on domain.com 465 I get an error saying "telnet is not recognized as an internal or external command"
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  • cPRex Jurassic Moderator
    That sounds like you need to enable the software using the first guide I linked.
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  • PostAlmostAnything
    What specific settings are you using in your Outlook? If you're connecting securely either through tls_on_connect or TLS upgrade - has the secure certificate for the used hostname expired? Do you have cPanel automatic updates enabled? No real clue if cPanel recently pushed out any updates, the cPanel folks here would have a better idea of that. Do you have automatic OS updates enabled? Perhaps an update to OpenSSL or Dovecot happened that you were unaware of.

    I am using every specific Outlook setting that I've always used. If any certificates are expired it would be due to AutoSSL screwing up again, but it doesn't appear that way. I don't know if I have cPanel auto-updates enabled or not. Again, don't know about automatic OS updates either. I assume cPanel must be configured out of the box to do auto-updates because that is how software is supposed to be setup by default.
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  • PostAlmostAnything
    Can you try the test with the current port you're using? That may be 26 or some other alternate port. It's also important to note that we don't provide your hosting - we do create the cPanel software that your hosting provider users, but we have no control over your personal server or hosting environment.

    I host on an unmanaged VPS with root access which I have not changed in awhile. My hosting company is hands off, so that means they probably changed nothing at all. What software did you link to? My SMTP port is port 465
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  • PostAlmostAnything
    Turns out telnet has to be enabled in Windows Control Panel and is not enabled by default. Now I get the following for telnet domain.com 465 without quotes "_"
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  • sparek-3
    If your Outlook is configured to use port 465 then you are likely using tls_on_connect - so the telnet test to port 465 probably isn't going to tell you very much. Are you sure Exim is running? Have you restarted Exim? [font="courier new">/scripts/restartsrv_exim Or there's probably a link in your WHM to do this too.
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  • PostAlmostAnything
    If your Outlook is configured to use port 465 then you are likely using tls_on_connect - so the telnet test to port 465 probably isn't going to tell you very much. Are you sure Exim is running? Have you restarted Exim? /scripts/restartsrv_exim Or there's probably a link in your WHM to do this too.

    What is Exim? I've seen references to it before, but have never had a reason to ask what it is before
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  • PostAlmostAnything
    Also, please don't give me console commands as if I know what part of a linux machine they might refer to. I would have to login via WHM and then use the terminal just to input them and I hate doing that. Could you please describe how to do the same things in WHM or cPanel without the terminal from now on?
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  • PostAlmostAnything
    Accidental comment, but couldn't find option to delete, just to edit.
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  • sparek-3
    Probably not the best thing to run on an unmanaged service if these commands and items are foreign to you. That may sound condescending, and I don't mean for it to, but there's some truth in that. If you're going to use an unmanaged or self-managed system you probably need to know how to diagnose issues like this.
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  • PostAlmostAnything
    What is Exim? I've seen references to it before, but have never had a reason to ask what it is before

    Yes, it does SSL to connect. The exact Outlook option used is called SSL/TLS, but that should not be a problem because this server has been running email exactly the same way for over a year until yesterday.
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  • PostAlmostAnything
    Probably not the best thing to run on an unmanaged service if these commands and items are foreign to you. That may sound condescending, and I don't mean for it to, but there's some truth in that. If you're going to use an unmanaged or self-managed system you probably need to know how to diagnose issues like this.

    I thought if I ran an unmanaged system all I should need is software like cPanel to manage email for me. Its not that I cannot use the terminal, but I use it rarely due to it not being necessary unless cPanel screws up somehow.
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  • PostAlmostAnything
    Isn't there an option (or at least there should be) to restart Exim WITHOUT the terminal? I seem to recall seeing just the thing in WHM last night (see below): ERROR! Cannot find option to add image to comment. Why give me a command line directive instead of telling me to open WHM, find the part featured above, and use it?
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  • sparek-3
    Well... cPanel is just a tool. Now, you can argue that cPanel has marketed itself as some magic tool that automatically does everything you ever need - I might join you in that argument. But in the end it's just a tool. With ANYTHING that is on the Internet there is no such thing as a "install this and leave it and never have to worry about it ever again!" Has cPanel and other control panels peddled themselves as such? Maybe. But it's a marketing scheme - it doesn't make it true.
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  • cPRex Jurassic Moderator
    cPanel makes managing many things on the server easier, but it doesn't replace server management troubleshooting skills when things go wrong. You can restart the Exim mailserver from WHM >> Restart Services.
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  • PostAlmostAnything
    Well... cPanel is just a tool. Now, you can argue that cPanel has marketed itself as some magic tool that automatically does everything you ever need - I might join you in that argument. But in the end it's just a tool. With ANYTHING that is on the Internet there is no such thing as a "install this and leave it and never have to worry about it ever again!" Has cPanel and other control panels peddled themselves as such? Maybe. But it's a marketing scheme - it doesn't make it true.

    Well, you're probably right, but for something as simple as email they market themselves as a total package. All I should have to do is configure the email account in cPanel, plug the info into Outlook, and connect. That is all I've ever had to do before, so why would cPanel change it now?
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  • sparek-3
    Why give me a command line directive instead of telling me to open WHM, find the part featured above, and use it?

    I avoid the WHM as much as possible. I manage over 40 servers - I can't log into the WHM every single time on every single server to perform tasks. Shell and command-line makes everything so, so, so much easier for people like me. In root's WHM there should be a link under Restart Services for Mail Server (Exim) that SHOULD restart exim.
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  • PostAlmostAnything
    cPanel makes managing many things on the server easier, but it doesn't replace server management troubleshooting skills when things go wrong. You can restart the Exim mailserver from WHM >> Restart Services.

    I tried that last night. Nothing, so I tried a forceful reboot today and also nothing.
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  • cPRex Jurassic Moderator
    why would cPanel change it now?

    We haven't. Something is broken either on your machine, or your connection to that network.
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  • PostAlmostAnything
    I stopped using HmailServer for the domains I use to host .Net sites because at the time cPanel was much easier AND didn't land in the junk mail folder as much (today however every email I send myself lands in junkmail no matter how many times I mark them as not junk). Now I am wondering if I should use Hmail
    We haven't. Something is broken either on your machine, or your connection to that network.

    Are there any new security features that might block access to my IP?
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  • cPRex Jurassic Moderator
    We're getting pretty far off track here, so let's try and focus back in on the original issue. What error message do you get from Outlook? Did the telnet test not properly complete? Normally you should get some output similar to this: "connected to mailserver.domain.com - Escape character is ] - we do not authorize the use of this system to transport unsolicited and or bulk email" If that didn't happen, you couldn't connect from your machine to the server, which could indicate a firewall problem on the server, or a change on the network outside of your control. As a test, you can run the same command with port 80 from your local workstation to see what a working connection looks like: telnet domain.com 80
    as port 80 is the connection to the webserver. If your IP was blocked, you wouldn't be able to access WHM or websites.
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  • PostAlmostAnything
    We haven't. Something is broken either on your machine, or your connection to that network.

    I made no changes to my machine at all let alone any that could break it.
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  • sparek-3
    Did the telnet test not properly complete? Normally you should get some output similar to this: "connected to mailserver.domain.com - Escape character is ] - we do not authorize the use of this system to transport unsolicited and or bulk email"

    You won't get this if you connect via telnet with a tls_on_connect port - which port 465 is pretty standard in that regard - think that's the cPanel default. You'll get a [font="courier new">Escape character is '^]'. But you won't get an SMTP banner. But I suppose that would be enough to determine if the IP or service is blocked. You'd have to use something like openssl's s_client [font="courier new">openssl s_client -connect domain.com:465 to get a response from a tls_on_connect port.
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  • sparek-3
    If you are using any firewall software you would need to determine if your IP address is being blocked. You will ultimately need to review the exim logs to see what is happening when you try to connect to the SMTP service, assuming your IP address is not blocked. There's just really not enough information here to diagnose the issue.
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