Why pointless spam????

I get lots of spam mails with nonsense text and a gif file as attachment (I have Windows to show the file type, naturally, so it must be a gif file and not a disguised .exe file; and my antivirus app doesn’t yell, as it does when it finds a virus in an attached zip file).
And I just get it! What is the purpose of sending me such mail? There isn’t any links ‘they’ want me to go to, and I can only scratch my head.
I use a probably unknown text only mail app (Becky), so I never see the html version of these meaninless spams.
Can anyone explain why anyone would go to the trouble of mailing such nonsense with – seemingly – no purpose at all? Thanks.
Regards
Finn Ekberg Christiansen