Hello KDE community!

I am running Manjaro KDE Plasma and I have set up Kmail for two accounts: 1) my Microsoft institutional e-mail and 2) and my personal Gmail one.

Kmail works fine regarding receiving e-mails, but I cannot send e-mails at all and I receive this error and I don't know what this is about: "Could not compose message: Inappropriate ioctl for device".

I was not able to find information about this on web or on this forum.

Any piece of help will be greatly appreciated and please provide some baby steps as I am new to Linux in general.
Thank you.

My specs are:
Operating System: Manjaro Linux
KDE Plasma Version: 5.24.2
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.2
Kernel Version: 5.15.25-1-MANJARO (64-bit)
Graphics Platform: X11
Processors: 6 × Intel® Core™ i5-9400F CPU @ 2.90GHz
Memory: 15,6 GiB of RAM
Graphics Processor: NVIDIA GeForce GTX 1650/PCIe/SSE2