[Users] Error from sudo apt-get update

[Rolf Turner]

Since I installed claws-mail from a repository (via sudo apt-get
install ...), every time I do "sudo apt-get update" I get an error
message:

> Err:18 http://ppa.launchpad.net/ubuntuhandbook1/claws-mail/ubuntu
> Bionic Release         
> 404  Not Found [IP: 2001:67c:1560:8008::15 80]

and at the end:

> E: The repository
> 'http://ppa.launchpad.net/ubuntuhandbook1/claws-mail/ubuntu bionic
> Release' does not have a Release file.
> N: Updating from such a repository can't be done securely, and is
> therefore disabled by default. N: See apt-secure(8) manpage for
> repository creation and user configuration details.

This worries me a bit.  Can anyone suggest whom I should contact about
trying to get this error fixed?

Thanks.

cheers,

Rolf Turner

-- 
Honorary Research Fellow
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276