1) On my system, when there is an eml-file
that is somehow not perfect, the program stalls.
It mentions connection problems however.
But when I remove the eml-file with problems,
it uploads the whole batch fine.

It would be better if it just skips and isolates
the corrupt eml-file, renames it or places
it in a folder called 'error',
and completes the other eml-files.

2) The error in my eml file is likely
a result of me spitting them as such
from a FileMaker database,
which I used for e-mail before Gmail.

And there are probably more people who
use your program not for backing up,
but for just uploading eml-files from
other e-mail accounts and clients.

I think you should therefor not
market your program is merely a backup-tool.
There could even be féwer people who
are interested in backing up up Gmail.

After all, Gmail's reputation is nearly flawless.

Looking around online,
there are indeed many people trying to upload
their old e-mails.

with jolly greetings,
Tristan Laurillard