Notes (IBM Notes now) allows a user to add other mail files to look into, or other calendars.
Security is managed by user themselves, granting you access to their mail file. One would think, the feature is well thought through, but on at least two occasions, you might get into trouble and at first hand might not see the reason.
case SWIFT File:
if you have installed Swift File (you know, the “guessing tool” that guesses the folder you might want to put your new mail into in order to forget it ;-)), and enabled your mail file to use Swift. In this case, no problem.
case SWIFT File and Access to other mail/calendar:
better enable all mail files you have access to for Swift. If you don’t, probability is high that your client crashes when you try to close it (at the end of a day, you want to leave and not wait for NSD to write the whole complaint to disk). Or don’t add other mail or calendar. People are not often aware of the fact that they have links to other mail on their workspace just because of a quick look in somebodies calendar.
If you have access to another mail file and your mail policy says “Show Quota Indicators on client” (you can find that in the Desktop Policy, tab “Mail”) then Notes seems to try to update something in each mail file you open, but you only have reader access. It then says something like “too many mail rules or you are you are over quota”. More verbose, of course, and misleading.
The german version:
For people using other mail either give them a higher access level to the targeted mail file or kick the policy. Access level is usually done in “More.Preferences.AccessAndDelegation” and mostly sets readers only. You can give other people the right to edit, which would enable them to use the mail file.
Edit: IBM support found the code really quick after a small hint.