Thunderbird 115.13.0 (64-bit) on Linux using filters to forward to an alias on localhost ignores the nsswitch.conf settings and attempts to send the email to the main configured SMTP server instead of via the localhost SMTP server for the email address being forwarded to, which is process@localhost. This process alias is defined in the /etc/aliases file and my nsswitch.conf file has file dns as the hosts: values. The alias being sent to is supposed to process the email being forwarded and write the result to a file.