Two accounts, same Outlook, same PST change - one keeps receiving, the other goes silent. The deciding factor is a column most people never read: the account Type. This page explains, in plain terms, why POP mail has a delivery location that can be mispointed while IMAP and Exchange mail physically cannot, so you stop applying POP fixes to IMAP problems and the other way round.
The short version deserves repeating: delivery location is a POP-only concept. POP was designed to empty a server mailbox into a local file, so Outlook must know which file. IMAP was designed to leave mail on the server and mirror it, so there is nothing to aim. Once that is clear, half the confusion around PST changes disappears.
Example account list. The Type column explains the whole mystery: only the POP3 row has a delivery location that a PST change can move.
POP downloads mail into a data file on your PC - and you, or Outlook, choose which file. IMAP and Exchange mirror the server - Outlook keeps a synchronised copy in the account own OST file, and the "real" mailbox lives on the server. Everything else flows from that: a delivery location exists only where a choice of destination exists, and only POP makes that choice.
When a new PST is added or set as default, Outlook updates the delivery target for POP accounts to the Inbox of the default file. The POP server does not care and Outlook reports no error - downloads succeed, they just land in the new file. IMAP and Exchange accounts are untouched by the same change because their mail flows into their own OST stores regardless of which PST is default. Same event, completely different consequences - decided entirely by that Type column.
Usually nothing at all, and it is worth saying plainly. The IMAP folders you see are the server folders; the added PST simply appears in the folder pane as an extra, mostly empty file for archives. If an IMAP account stops showing mail after some change, suspect the sync slider (Mail to keep offline), a filtered view, or a send/receive error - not the PST. Do not delete and recreate the account as a first move; the server copy makes most IMAP problems recoverable with patience.
Many real profiles hold one POP account and one IMAP account side by side. After a PST change, the IMAP account keeps working perfectly while the POP account silently files into the wrong PST - which produces the confusing report "some mail arrives, some does not". It is not random and it is not the server. It is one account type obeying a delivery setting the other type does not have. Diagnose per account, never per profile.
The full fix, shown live in Outlook - the account settings screens, the delivery location and the test mail arriving - is in the video above.
Watch Full VideoIn the folder pane, IMAP and Exchange accounts show the account email address as the top-level name with server folders under it, and their data file is an OST. A POP account delivers into a PST - often labelled Outlook Data File or Personal Folders. The certain check is still the Type column in Account Settings, which takes ten seconds.
Not as live delivery. IMAP mail stays in its own store so it can mirror the server. You can copy or archive IMAP mail into a PST - with rules, AutoArchive, or by dragging folders - and many people keep yearly archives that way. But the Inbox itself always syncs to the OST, never to a PST.
No. The new Outlook is cloud-based: accounts connect directly to their servers and there is no PST delivery location at all. This whole problem class belongs to classic Outlook with POP accounts - which is exactly why it survives in so many offices that still run POP.