This one ftp://ftp.swfwmd.state.fl.us/pub/outgoing/012715.pdf seems to work though (username anonymous). Not sure if that's because that one is password-protected and or it's because viewing ftp://ftp.swfwmd.state.fl.us/pub/outgoing/ (the directory the pdf is in) isn't disabled like it is with ftp://ftp.ams.org/ams/doc/amscls/.
Opera mail already has mbox import/export support. See https://www.reddit.com/r/operabrowser/wiki/m2tips/export_messages.
Also, when you ctrl + s to save a single message, it saves it as an mbox file. You can edit the file with a text editor and remove the "From " line at the top. Then, you can rename the file to have a .eml extension and you have an eml file. There are also mbx2eml and em2mbx converters on the net.
For importing mbox, see "Menu -> settings -> import and export -> import mail -> import generic mbox". See https://www.reddit.com/r/operabrowser/wiki/m2tips/import_from_thunderbird as an example.
@leocg Thanks a lot for the explanation. I disagree, however, very much about your statement "People nowadays almost don't use email to communicate between them so developing a email client doesn't make much sense.". In my experience that is not the case. So a powerful email client is a very important offer Opera should make.
There's a little bit of supported customization here by editing accounts.ini. See http://www.opera.com/help/tutorials/mail/advanced/#messageid-syntax and http://www.opera.com/help/tutorials/mail/advanced/#personal-messageid.
@leocg Yes. The label concept is a very interesting addition. But most users want to have the ability to create folders. A realization with a database is fine but should be transparent to the user. Folders can simply be implemented using the database technology.
If I'm not wrong, that has been asked.
Meanwhile, you can use a switch to do that.
You can find more info in the signatures link "Test profile" if you are interested.
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