Given that they appear to be an exclusively Windows-using organisation, it's highly likely that they use MS Exchange.

Thunderbird uses Internet standards POP, IMAP & SMTP. MS Exchange can use these but the admin may not have enabled them. It's possible that your Android mail client has the ability to use Microsoft's proprietary protocols in order to work with Exchange.

If the standard protocols are not available, you could use the Davmail or Exquilla add-ons in Thunderbird to allow it to appear to be an Exchange-compatible mail client. I use Davmail successfully to do this at my workplace.

Bear in mind that if they don't use POP etc, it's unlikely that they'll be allowing external connections to in-house mail accounts. The usual ways to permit such connections are VPN and/or OWA.

Thank you Zenos, I now understand better, how Exchange Server works. I will try one of your methods. If I run into any problem, I hope you can offer further advice.

Hi Zenos, I have installed DavMail but how do I know the correct values to use for the Gateway Settings?

you could try connecting using this add-on https://addons.mozilla.org/en-US/thunderbird/addon/exquilla-exchange-web-services/?src=ss

Zenos said

If the standard protocols are not available, you could use the Davmail or Exquilla add-ons in Thunderbird to allow it to appear to be an Exchange-compatible mail client. I use Davmail successfully to do this at my workplace. Bear in mind that if they don't use POP etc, it's unlikely that they'll be allowing external connections to in-house mail accounts. The usual ways to permit such connections are VPN and/or OWA.

Hi Zenos, there is a new problem. I have got Davmail working at home but not at the office. I also note that I can't access OWA at work. Why is that?