I have LOADS of aliases and quite a few mailboxes and your importer got flooded by the HUGE import and the reason I was ‘forced’ to import all, was that in the import tool, you actually did not add the basics!
i.e. Select all, De-select all.
I have LOADS to import and wanted to see how it behaved with this load.
I went to import a few only and they are all PRE-selected and CANNOT DE-select all at once!
I am mean that is 1980s right?
It will take me ages to manually deselect all and then select a few!
By the way, my computer is FAST and there is plenty of memory too and your program [while attempting import] was using only ~300kb and then went up an up to nearly 2Gb - then I left it alone!
PS why do you use LIGHT Orange on a white background o your Community pages?
It is unreadable.
Just adding an import link ‘within’ each account Settings would have solved it straight away!