You guys have saved my life before, thought maybe I'd temp fate again. (Running latest/updated Windows 10 using Outlook Pro 2016.) Just renamed the folder that my Outlook.pst file is traditionally stored in (alongside other dated backups). Outlook itself was closed during. On first load following, Outlook asked for the location of said .pst file, which I provide. It then resumes loading without any issues. The custom folders are all there, and seem to contain the last emails I remember receiving. Even the .ost connections to my legacy hotmail accounts are running fine (even interacted with new mail there). The ONLY issue I'm having is sending/receiving with the SMTP accounts (which are usually the easy ones). Not one of them is able to retrieve new emails. The error generated is in the following form : ! Task 'account1@domain.com - Sending' reported error (0x800401F) : 'Outlook data file cannot be accessed.' ! Task 'account1@domain.com - Receiving' reported error (0x800401F) : 'Outlook data file cannot be accessed.' ! Task 'account2@domain2.com - Sending' reported error (0x800401F) : 'Outlook data file cannot be accessed.' ! Task 'account2@domain2.com - Receiving' reported error (0x800401F) : 'Outlook data file cannot be accessed.' etc. The .pst file itself was never touched (it's the folder I renamed) and in both cases, read-only + hidden are both unchecked in the properties dialog. Also went over the account settings; server names and port numbers all seem fine. (Apologies if I misused a term or two, or if I've broken site etiquette posting this here. I'm a little out of my depth in these matters.) Any suggestions on how I can un-break this thing? Thanks!