Using alias made with Runbox in Thunderbird

I joined Runbox today and am now testing. What is very important to me - besides privacy - is the use of aliases. I have another email provider where I can create aliases and these are addresses that I can retrieve separately in Thunderbird. For example: my main address is Lieke@iknoemmaarwat.nl and an alias is Hyfija@iknoemmaarwat.nl. I can retrieve both addresses separately in Thunderbird.

I have now created an alias (over an hour ago) in Runbox, but I cannot retrieve it in Thunderbird the way I did with my standard provider. I do receive the emails that I send to the alias on the main account of runbox. That is fine, but my specific question is: if I cannot create an alias as an account in Thunderbird, how can I send an email from Thunderbird with the account of the alias?

Hello and welcome to the forum. We have a guide to doing this in Thunderbird. The guide is a bit old but it should still be more or less the same procedure. IMAP for Mozilla Thunderbird | Runbox Help

I hope that helps.