Issue Unable To Connect with IMAP via Mail Client (Webmail Works)

[scottyp]

I have a VM on Google Cloud running Ubuntu 18.04.5. Having an issue setting up iOS (mobile) and Thunderbird (desktop) mail client for a domain, which tells me it’s not the client itself nor the device that’s the problem.

I’ve tried with and without VPN.
I’ve tried to disable Failed2Ban temporarily.
I’ve tried the hostnames mail.domain.com and simply domain.com without resolution. I’ve tried resetting the mail account password.

Initially it tells me that it cannot connect with SSL and to try without, even though I have a wildcard SSL from Let’s Encrypt. Then it’s still not able to connect.

Webmail works fine.

Perhaps someone in the community can point me in the right direction?

 

[tlatch52]

Do you have your DNS set up correctly?

How to manage mail autodiscover in Plesk Obsidian?

Applicable to: Plesk Obsidian for Linux Question How to manage mail autodiscover in Plesk? Answer Autodiscover is enabled by default on all new Plesk Obsidian installations for all domains. For...

support.plesk.com

- Plesk does not use "mail.example.com" or "imap.example.com". It uses domain name itself like "example.com" as SMTP/IMAP hostname for automatic configuration.

- A valid SSL certificate is required. Make sure you have one assigned under Mail Settings tab or issue it using "SSL It" including option "Assign the certificate to mail domain".

- Go to Tools & Settings > Mail Server Settings > Settings tab > General options > Enable the Enable mail autodiscover option.
- Next, enable it for the particular domain:
- Enable it under Domains > example.com > Mail Settings. Activate option Enable mail autodiscover

I use Thunderbird desktop and iOS default mail for mobile and with autodiscover enabled all I have to do is put in the email address + password and it populated the server hostname stuff for me automatically. If you don't want to use autodiscover it could be maybe the port number you're using during manual setup (465 or 587). Most likely something DNS or SSL related though.

Double check your SSL also, there is an arrow on the certificate page with the additional hidden option for mail that I had forgot about once before.




You could always try a quick server reboot as well. Hope that at least points you in the right direction. Good luck!

 

[mow]

Initially it tells me that it cannot connect with SSL and to try without, even though I have a wildcard SSL from Let’s Encrypt. Then it’s still not able to connect.

Webmail works fine.

Perhaps someone in the community can point me in the right direction?

Is there a firewall anywhere between you and the server?

Try connecting to the ports with telnet or something, e.g. telnet domain.tld 993. If you get Connection refused or Connection timed out, you're firewalled. Or somehow managed to configure dovecot to only listen on localhost. webmail connects to localhost on loopback, which usually isn't restricted.

 

[Olma67]

Hi!

I have the same issue after migrating 2 sites to an already smooth running server.
After migration, the owner of these two sites complained about a non-functional mailserver because he doesnt receive any e-mail and Aplle Mail did not connect to the server. So I double checked the settings and ports on the client side but everything was fine. But Apple Mail said that the mailserver did not respond. Sometimes a message pops up like this one: "An SSL error has occurred. A secure connection to the server cannot be established."
During my investigation whats going on I mentioned that all hosted websites of this server couldnt be displayed by any browser running on MacOS or iOS. (Server refuses connection). On Windows/Linux/Android... everything is fine. The websites can be browsed and the mail-server delivers the e-mails.
All domains are fully secured by Letsencrypt (Mail, wildcard, webmail, etc.).
It seems, that there is maybe something going on with the generated Letsencrypt certificates and Apple.
Does anyone has a clue? A hint? An idea?

Thank you very much!

 

[MrWrighty]

Hi!

I have the same issue after migrating 2 sites to an already smooth running server.
After migration, the owner of these two sites complained about a non-functional mailserver because he doesnt receive any e-mail and Aplle Mail did not connect to the server. So I double checked the settings and ports on the client side but everything was fine. But Apple Mail said that the mailserver did not respond. Sometimes a message pops up like this one: "An SSL error has occurred. A secure connection to the server cannot be established."
During my investigation whats going on I mentioned that all hosted websites of this server couldnt be displayed by any browser running on MacOS or iOS. (Server refuses connection). On Windows/Linux/Android... everything is fine. The websites can be browsed and the mail-server delivers the e-mails.
All domains are fully secured by Letsencrypt (Mail, wildcard, webmail, etc.).
It seems, that there is maybe something going on with the generated Letsencrypt certificates and Apple.
Does anyone has a clue? A hint? An idea?

Thank you very much!

I had similar issues after migrating a number of sites migrated from a cPanel based VPS. None of the email accounts would connect via Outlook, Apple or Android reliably. In the end I resorted to this fix which appears to have done the trick, but relates to Plesk Onyx rather than Obsidian. https://support.plesk.com/hc/en-us/...-authentication-failed-authentication-failure.

After this fix, all clients can connect send and receive emails.