Yahoo Email authentication failed

Hi,

I'm using 2 Rocketmail/Yahoo POP accounts by an Arch Linux desktop machine with 2 MUAs, Claws and Evolution. Due to Yahoo "hiccups" every now and then I need to delete and create new app passwords.
At the moment both MUAs are able to retrieve mails from both Rocketmail/Yahoo accounts. Evolution can send mails by both accounts and Claws is able to successfully send using one account, but the other account always retus

** error occurred on authentication
***...

Yahoo Email authentication failed WordPress ...