Solved Thunderbird issue

[Danbor]

Hello all. I'm having an issue with Thunderbird mail on one of my computers and am hoping someone can point in the right direction to start troubleshooting it. I haven't yet checked to see it the problem is on the laptop also, but I'll leave that for now.
Ok, both computers are running Mint 22.2. Both running Thunderbird Mail version 128.14.0esr From what I can tell, all server and account settings are the same. I'm using Nord VPN, have been for years so I don't think that is the issue.
Computer 01 is the one I use most frequently, and the one I usually use for my emails.
Sometime in the last week, every time I try to check for messages on computer 01, thunderbird gives the notification "connection to server pop.mail.yahoo.com timed out". Same mesage when attempting the gmail account, of course the notification is changed to reflect the different accout. However, computer 02, with the same settings, running on the same home network, recieves emails just fine. Paint me confused. Researching on my own has led me nowhere but into further confusion. Most sites I've been to say my ISP is probably blocking port 25 but I don't know how to check that, nor how to unblock it if it is. Is port 25 on each computer or is it on the router? Must be on each computer as computer 02 works fine. Or that may not be the problem at all. Sigh.
Anyone have any ideas on where to start troubleshooting this?

 

[osprey]

Most sites I've been to say my ISP is probably blocking port 25 but I don't know how to check that, nor how to unblock it if it is. Is port 25 on each computer or is it on the router? Must be on each computer as computer 02 works fine. Or that may not be the problem at all. Sigh.
Anyone have any ideas on where to start troubleshooting this?

To start troubleshooting you could consider the following.

One command to see what ports are in use on the machine is:

$ ss -tulpen
Netid             State              Recv-Q             Send-Q                         Local Address:Port                         Peer Address:Port            Process                                                                                                    
udp               UNCONN             0                  0                               127.0.0.1%lo:53                                0.0.0.0:*                                    ino:17588 sk:1 cgroup:/system.slice/connman.service <->                               
udp               UNCONN             0                  0                                    0.0.0.0:68                                0.0.0.0:*                                    ino:16585 sk:2 cgroup:/system.slice/[email protected] <->                           
udp               UNCONN             0                  0                                    0.0.0.0:5353                              0.0.0.0:*                                    uid:103 ino:10483 sk:3 cgroup:/system.slice/avahi-daemon.service <->                  
udp               UNCONN             0                  0                                   [::1]%lo:53                                   [::]:*                                    ino:17592 sk:4 cgroup:/system.slice/connman.service v6only:1 <->                      
udp               UNCONN             0                  0                                       [::]:5353                                 [::]:*                                    uid:103 ino:10484 sk:5 cgroup:/system.slice/avahi-daemon.service v6only:1 <->         
tcp               LISTEN             0                  128                                  0.0.0.0:22                                0.0.0.0:*                                    ino:13791 sk:6 cgroup:/system.slice/ssh.service <->                                   
tcp               LISTEN             0                  4096                               127.0.0.1:631                               0.0.0.0:*                                    ino:31689 sk:7 cgroup:/system.slice/cups.service <->                                  
tcp               LISTEN             0                  10                              127.0.0.1%lo:53                                0.0.0.0:*                                    ino:17596 sk:8 cgroup:/system.slice/connman.service <->                               
tcp               LISTEN             0                  128                                     [::]:22                                   [::]:*                                    ino:13793 sk:1001 cgroup:/system.slice/ssh.service v6only:1 <->                       
tcp               LISTEN             0                  10                                  [::1]%lo:53                                   [::]:*                                    ino:17600 sk:1002 cgroup:/system.slice/connman.service v6only:1 <->                   
tcp               LISTEN             0                  4096                                   [::1]:631                                  [::]:*                                    ino:31688 sk:1003 cgroup:/system.slice/cups.service v6only:1 <->

In the output one can see the ports in the column: Local Address:Port. The output shows what's listening on the machine, and on the far right side, the process that is using the port.

In the output shown, there is no mailer or mail server, so your machine's output will differ in that respect as well as others. You can check to see if there's a difference between the machine that works and the one that is troublesome.

ISP's commonly block port 25 to protect against spam and whatever other vulnerabilities are there.

The ISP's port should be visible on the machine that works in the output from the ss command above. Otherwise one can check the ISP's email, SMTP settings.

Here's a little table from my notes which may be dated, but still useful:

Purpose                Port          Description
=======                ====          ===========
SMTP (sending)         25           Legacy; often blocked by ISPs
SMTP (submission)      587          Recommended for client sending
SMTPS (secure)         465          SSL/TLS encrypted  SMTP
IMAP (receiving)       143          Plain IMAP
IMAPS                  993          IMAP over SSL/TLS
POP3                   110          Plain POP3                                  
POP3S                  995          POP3 over SSL/TLS

 

[theLegionWithin]

if the environment is the same on each computer (ie: both using Nord, both on the same local network, same distro, same software in use, etc) but one works and the other doesnt, then the issue isnt with the network or the config, it's an issue with the one computer that doesnt work - probably software but maybe hardware. I'd recommend trying to use a different network adapter, and if that doesnt work, try to create a new user account on the computer and then setup/configure your mail client when logged in as that user.

if the issue persists, a reimage/reinstallation of the distro is may be a quick solution.

 

[Danbor]

I'm thinking it's a software issue. Fired the computer up this morning and Thunderbird worked fine. Go figure.
I did fix one problem though. Scrolling around and the mouse pointer locked up for a couple of minutes, thoughts of display issues or memory loss went through my head. Then I had the idea to replace the battery in the mouse. Works fine again. Sometimes it's the simple things.
Pretty sure the mouse will still be ok tomorrow. Thunderbird? We'll see.

 

[Danbor]

To start troubleshooting you could consider the following.

One command to see what ports are in use on the machine is:

$ ss -tulpen
Netid             State              Recv-Q             Send-Q                         Local Address:Port                         Peer Address:Port            Process                                                                                                   
udp               UNCONN             0                  0                               127.0.0.1%lo:53                                0.0.0.0:*                                    ino:17588 sk:1 cgroup:/system.slice/connman.service <->                              
udp               UNCONN             0                  0                                    0.0.0.0:68                                0.0.0.0:*                                    ino:16585 sk:2 cgroup:/system.slice/[email protected] <->                          
udp               UNCONN             0                  0                                    0.0.0.0:5353                              0.0.0.0:*                                    uid:103 ino:10483 sk:3 cgroup:/system.slice/avahi-daemon.service <->                 
udp               UNCONN             0                  0                                   [::1]%lo:53                                   [::]:*                                    ino:17592 sk:4 cgroup:/system.slice/connman.service v6only:1 <->                     
udp               UNCONN             0                  0                                       [::]:5353                                 [::]:*                                    uid:103 ino:10484 sk:5 cgroup:/system.slice/avahi-daemon.service v6only:1 <->        
tcp               LISTEN             0                  128                                  0.0.0.0:22                                0.0.0.0:*                                    ino:13791 sk:6 cgroup:/system.slice/ssh.service <->                                  
tcp               LISTEN             0                  4096                               127.0.0.1:631                               0.0.0.0:*                                    ino:31689 sk:7 cgroup:/system.slice/cups.service <->                                 
tcp               LISTEN             0                  10                              127.0.0.1%lo:53                                0.0.0.0:*                                    ino:17596 sk:8 cgroup:/system.slice/connman.service <->                              
tcp               LISTEN             0                  128                                     [::]:22                                   [::]:*                                    ino:13793 sk:1001 cgroup:/system.slice/ssh.service v6only:1 <->                      
tcp               LISTEN             0                  10                                  [::1]%lo:53                                   [::]:*                                    ino:17600 sk:1002 cgroup:/system.slice/connman.service v6only:1 <->                  
tcp               LISTEN             0                  4096                                   [::1]:631                                  [::]:*                                    ino:31688 sk:1003 cgroup:/system.slice/cups.service v6only:1 <->

In the output one can see the ports in the column: Local Address:Port. The output shows what's listening on the machine, and on the far right side, the process that is using the port.

In the output shown, there is no mailer or mail server, so your machine's output will differ in that respect as well as others. You can check to see if there's a difference between the machine that works and the one that is troublesome.

ISP's commonly block port 25 to protect against spam and whatever other vulnerabilities are there.

The ISP's port should be visible on the machine that works in the output from the ss command above. Otherwise one can check the ISP's email, SMTP settings.

Here's a little table from my notes which may be dated, but still useful:

Purpose                Port          Description
=======                ====          ===========
SMTP (sending)         25           Legacy; often blocked by ISPs
SMTP (submission)      587          Recommended for client sending
SMTPS (secure)         465          SSL/TLS encrypted  SMTP
IMAP (receiving)       143          Plain IMAP
IMAPS                  993          IMAP over SSL/TLS
POP3                   110          Plain POP3                                 
POP3S                  995          POP3 over SSL/TLS

Thanks for the assist. Forgive me, but another question. In the example you offered, and the output of the command I entered myself, Just where does it list the human readable "port number", example, "25"? I do not know how to translate the listed figures into something I can read.

 

[osprey]

Thanks for the assist. Forgive me, but another question. In the example you offered, and the output of the command I entered myself, Just where does it list the human readable "port number", example, "25"? I do not know how to translate the listed figures into something I can read.

In the following extract from the output shown in post #2, the port numbers are all in a column under the heading: Port

   Local Address:Port
    127.0.0.1%lo:53
         0.0.0.0:68
         0.0.0.0:5353
        [::1]%lo:53
            [::]:5353
         0.0.0.0:22
       127.0.0.1:631
    127.0.0.1%lo:53
            [::]:22
        [::1]%lo:53
           [::1]:631

These are the ports that the machine is using, and it's listening on those which are listed as: LISTEN, in the first column of the full output in post #2. The processes those ports are serving are in the last column of the full output in post #2.

 

[Trml]

I'm using Nord VPN, have been for years so I don't think that is the issue.

Even with good experiences, don't assume it. VPN support has increased stability tremendously on Linux in the last decade, but there are hickups left no matter what sort (ovpn, wg, tcp/udp, ipsec, Nordvpn app or not, etc) you use.

As a simple example, the client upgrading kernel/network or vpn-related packages in the background may result in a stable vpn connection and routing table become dysfunctional, needing a vpn restart. An example that fixes itself with a reboot.

 

[Danbor]

Thanks for the assist ospry and Trml. I appreciate it.
It appears that the VPN is the guilty party. Thunderbird worked after bootup yesterday. Did not this morning. Rebooted and it's working.
As for the output of ss -tulpen, due to my old eyes, I failed at first to notice the colon between local address and port.
Getting old has it's downside, but it beats the alternative!