Simultaneous operations?

Can I work with an EagleFiler email library on other matters while it is, e.g., merging two mailboxes. Can I, for example, read, delete or move mail in other record items? I would think that some such operations would be dangerous.

Yes, you can continue working in EagleFiler while it’s merging, importing, etc. It won’t let you do anything dangerous (like emptying the trash) while the files are in use.