Now and then I get the question "I want to archive x mails. Is this going to work?"

The obvious and politically correct answer to this is "Of course".

But as usual this isn't so easy and the real answer is "It depends." There are 2 aspects to this: size of the archive and number of mails archived.

The size of the archive

The size of the archive affects the archiving speed a bit. And database operations like diagnosing and re-indexing take longer. Some customers are working with archives in the 20 GB range. The largest I know of has 500 GB!

The number of mails in an archive

The more mails you have in an archive the slower the archive becomes. Opening a mailbox, searching and sorting are affected by this. I'm working comfortably with an archives of about 100.000 mails.

Both factors are dependent on your hardware. I'm working with a very fast iMac from 2015. For testing I also use a MacBook Air which is way slower than the iMac.