The original aerc prototype was written in C. It wasn't great.

https://git.sr.ht/~sircmpwn/aerc-legacy

For anyone else wondering, it is written in Go.

Go it's ideal to replace old C/C++ based utilitarian software such as mail clients, music players and so on. For gaming and high performance needing tools such as the ffmpeg codecs and qemu, C/C++ have more sense there.

Any particular reason?

C is the best language for an application that spends all its time handling untrusted user input.

I see what you did there.