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Outlook 2016 v1908 can't send email "the operation failed. The messaging interfaces have returned an unknown error" RRS feed

  • Question

  • Outlook 2016 v1908 build 11929.20648
    Windows 10 1909 build 18363.959

    The operation failed.  The messaging interfaces have returned an unknown error"

    Can't send emails not even plain text with no signature block
    reinstalled office
    recreated local profile
    reimaged computer
    rebuilt the mailbox, reapplied permissions, cleaned up sip and smtp entries mailbox limits not exceeded.
    recreated the normalemail.dotm
    not using cached mode but tried both cached and non cached
    cleared the auto complete
    registered the dll
    ran switches cleanviews, resetfolders, noextensions,
    tried safe mode
    tried running as administrator
    no pst files
    no ost files
    ran sfc /scanow



    • Edited by N_C_ Friday, August 21, 2020 3:11 PM
    Thursday, August 20, 2020 11:54 PM

All replies

  • Got it sorted out, I forgot to run the switches for cleaning rules, cleanrules, cleanclientrules and cleanserverrules.

    Must have been a server rule still hanging around even though nothing was showing in Outlook or OWA

    Monday, August 24, 2020 9:41 PM