Hi

THis is the coredump detail on 2.3.17

Returning to 2.3.16 resolves the issue

(gdb) bt full
#0  fts_user_autoindex_exclude (box=<optimized out>, box@entry=0x55cf79d865c8) at fts-user.c:347
        fuser = <optimized out>
#1  0x00007f1f31198496 in fts_mailbox_allocated (box=0x55cf79d865c8) at fts-storage.c:806
        flist = <optimized out>
        v = 0x55cf79d865f0
        fbox = 0x55cf79d86bf8
#2  0x00007f1f31825ccc in hook_mailbox_allocated (box=box@entry=0x55cf79d865c8) at mail-storage-hooks.c:256
        _data_stack_cur_id = 5
        _foreach_end = 0x55cf79d77088
        _foreach_ptr = 0x55cf79d77078
        hooks = 0x7f1f311c6ba0 <fts_mail_storage_hooks>
        ctx = 0x55cf79d87df8
#3  0x00007f1f31820ec1 in mailbox_alloc (list=0x55cf79d7dfd8, vname=0x7f1f318e439e "INBOX", flags=flags@entry=0) at mail-storage.c:885
        _data_stack_cur_id = 4
        new_list = 0x55cf79d7dfd8
        storage = 0x55cf79d7e7e8
        box = 0x55cf79d865c8
        open_error = MAIL_ERROR_NONE
        errstr = 0x0
        __func__ = "mailbox_alloc"