Resolved Webmail working, IMAP/POP+SMTP via ThunderBird etc. failing

[tom-mcc]

Server operating system version

Ubuntu 20.0x

Plesk version and microupdate number

Obsidian 18.0.49 for linux

Hi folks,

I've been banging my head against a wall for the last little while, every time I come to this issue I can't figure out what's misconfigured. Also, it is a business's email server so I don't want to cause any disruption if I can avoid.

I can ping mail.quantumautomotiveni.com and it gets a response.

I was going to connect to client's mailboxes via ThunderBird in order to download and backup invoices with PDF attachments,

Unfortunately, ThunderBird simply will not connect to the Mail Server.

When I attempt to connect via ThunderBird, it doesn't find the configuration settings, or it simply times out, not connecting.

There were some issues with SSL and DKIM which has since been rectified, using CloudFlare.

Roundcube and Horde are working perfectly. These are configured to connect via localhost.

There are no firewall rules that seem to be excluding external connections to the mailserver -- in fact the Firewall add-on was not installed until I added it.

I have read that CloudFlare can cause issues with connecting to the Mail Server. I haven't been able to change any setting re: DNS or Email that may fix this.

If anyone could point me in the right direction, or offer some suggestions, please let me know.

If I can provide any log files too, I would be happy to,

unfortunately however, I don't seem to be able to access the root directory. I can FTP into the root dir of the website, but I cannot find the log files for Dovecot, Courier here.

I have used the virtual SSH via the plesk web panel -- it just prints "parallels" when I try to change directory to root.

I tried switching mail server to QMail etc., and this didn't work. It just broke webmail. I changed it back.

You can probably tell, I'm at quite a loss. I'm not that familiar with Plesk, and this server was not one that I set up.

Many thanks...
Tom.

 

[Peter Debik]

I've been banging my head against a wall

Won't help.

Unfortunately, ThunderBird simply will not connect to the Mail Server.
When I attempt to connect via ThunderBird, it doesn't find the configuration settings, or it simply times out, not connecting.

Have you checked that Fail2Ban on the server is not blocking your local IP for invalid login attempts? Tools Settings > Security > IP Address Banning. It is possible that this only blocks mail ports, but not web access, so that only the mail software on your computer can no longer connect due to previous false login attempts.

Roundcube and Horde are working perfectly. These are configured to connect via localhost.

Great, now you can be sure that the mail server is up and running. No need for further checks there.

There are no firewall rules that seem to be excluding external connections to the mailserver -- in fact the Firewall add-on was not installed until I added it.

Perfect, you have checked that no firewall is blocking port access. No need for further checks there.

I have read that CloudFlare can cause issues with connecting to the Mail Server. I haven't been able to change any setting re: DNS or Email that may fix this.

Do not route your hostname through Cloudflare. Connect to your mail server using the hostname, not a domainname. The hostname is the name that is used to login to Plesk, too (normally), like https://<hostname>:8443.

unfortunately however, I don't seem to be able to access the root directory. I can FTP into the root dir of the website, but I cannot find the log files for Dovecot, Courier here.
I have used the virtual SSH via the plesk web panel -- it just prints "parallels" when I try to change directory to root.

It seems that you try to access the root level through an SSH login of a subscription. That cannot work, because the subscription user is jailed to his subscription. In order to access your server, you can either use the SSH extension through Plesk GUI and go through Tools & Settings > Tools & Resources > SSH Terminal. You can also use a free client like PuTTY to connect to your server through SSH and use the credentials provided by your data center. After login you may need to escalate privilegs to root by running "su".

 

[tom-mcc]

Won't help.


Have you checked that Fail2Ban on the server is not blocking your local IP for invalid login attempts? Tools Settings > Security > IP Address Banning. It is possible that this only blocks mail ports, but not web access, so that only the mail software on your computer can no longer connect due to previous false login attempts.


Great, now you can be sure that the mail server is up and running. No need for further checks there.


Perfect, you have checked that no firewall is blocking port access. No need for further checks there.


Do not route your hostname through Cloudflare. Connect to your mail server using the hostname, not a domainname. The hostname is the name that is used to login to Plesk, too (normally), like https://<hostname>:8443.


It seems that you try to access the root level through an SSH login of a subscription. That cannot work, because the subscription user is jailed to his subscription. In order to access your server, you can either use the SSH extension through Plesk GUI and go through Tools & Settings > Tools & Resources > SSH Terminal. You can also use a free client like PuTTY to connect to your server through SSH and use the credentials provided by your data center. After login you may need to escalate privilegs to root by running "su".

Thanks so much for your reply, that is very helpful. I will check the fail2ban settings and then I will try connecting Thunderbird via hostname, without routing the hostname through cloudflare. I also never thought to add the port after the hostname. I'll also try using putty to access log files. That makes a lot of sense.

Cheers
Tom

 

[Peter Debik]

I also never thought to add the port after the hostname.

You don't want to add the port for the mail server. This was just an example which "hostname" is meant. Thre 8443 is a web server port. Not suitable for mail service.

 

[tom-mcc]

You don't want to add the port for the mail server. This was just an example which "hostname" is meant. Thre 8443 is a web server port. Not suitable for mail service.

Oh yes, of course. I will setting the ports depending on SSL/TLS or STARTTLs etc. Thanks

 

[tom-mcc]

Hi,

I disabled the DNS Proxy via cloudflare,

Adding the mail server hostname to thunderbird... here is the strangest thing... it makes me think that there is a firewall rule that I am missing... perhaps with the server host. It's connected to the host name but doesn't get further than the handshake presumably. The directories don't load and hence mail doesn't populate. It's like it's just about to load but something is stopping it.

 

[tom-mcc]

Hi,

I disabled the DNS Proxy via cloudflare,

Adding the mail server hostname to thunderbird... here is the strangest thing... it makes me think that there is a firewall rule that I am missing... perhaps with the server host. It's connected to the host name but doesn't get further than the handshake presumably. The directories don't load and hence mail doesn't populate. It's like it's just about to load but something is stopping it.

Hi,

I tried adding the account again and it worked, using the Hostname with STARTTLS and Normal password. Thanks for your help!