Consider to install the client in Multiuser mode. This way, all users will have their own client configuration settings (stored separately in their OS user profiles) . This should fix most of the mentioned issues if not all. Specifying user IDs in location documents is an ancient feature when Multiuser mode was not yet available. Nowadays, Locations better should be used to define different client usage scenarios for the same user.

Just make a copy of the current location and specify another ID file in it. Rename it accordingly. E.g. "Online - AJolie" and "Online - BPitt".

Perhaps that better should already happen at time of adding the additional invitee(s), before any invitation mail is sent to them. Perhaps by storing capacity of choosen room(s) within in the chair's meeting entry (for situations where a direct room capacity lookup in Domino Directory is not possible).

What about log_sessions=0, log_replication=0 and something like this. To remove clutter from the log. You can also reduce the number of days before log rollover, from the default 7 days to whatever you like.

Am I missing something, or isn't that already in Preferences > Windows and Themes > Theme? An admin needs to manage through updatesite.nsf to provision additional custom themes to the clients. User can then select from them.
For some example themes see { Link }

Hm, isn't this already working (at least as of 8.5.1)? There might be a delay because delegated ACL will be copied to the archive ACL at time of next archivation, not immediately at time of mail file delegation.

Launching catalog task on each replica server just to add a single new database to the catalogs is not only boring admin work but also has an unnecessary load overhead on the servers, especially on servers with many databases.
"Plan ahead" means being forced to unnecessarily split a single task into 2 tasks, to be processed at different days. Day 1: Initiate replica creation, set a reminder for the next day. Day 2: Send a link message to the users notifying them.
I want to create replicas and then almost immediately send notifications to users. Not one day later, or - if almost immediately but after forcing catalog to run - for the cost of unnecessary server load.
The in-memory catalog task would hook into database creation events only, nothing else. That should not - if at all - impact performance so much.

They should simply consider to "Use Operating System Settings" for proxy, just like they once invented "Use Operating System Settings" for the client timezone settings back in the ninetees.

We have created a "Create -> Mail -> Special -> Link Reminder" form in the mail template. Works almost similar to the "Link message" thingy, but instead creates a Reminder in the personal calendar containing a doclink to the document. Works with documents in any database, and requires only Reader rights on them.

Having Linux/Mac in mind - because it is COM it is Windows proprietary. This might be reason enough for IBM to not include it in the base packages.

You perhaps could consider to use Notes client broadcast or Sametime broadcast messages. They would appear for logged-in users only.

There are much more advantages:
No more need to sync contacts with the mail file, to have them available via iNotes, for sync with Blackberries/Lotus Traveler, to delegate access to the personal contacts to other people.
Absolutely the same is true with the Personal Journal/Notebook which matches perfectly the iNotes "Notebook" module.
When this is done, all the personal stuff of a user is in a single database. The local names.nsf then degrades to a client configuration database.

@2 We are using a similiar approach, but by configuring the ACLs of the catalog replicas differently on each server. Goal is that each location's catalog contains databases from user facing servers from that location only.

There would be no need to sync at all if the mail file were the ONLY place for personal contacts. The same applies to the content of personal journal. This would make the names.nsf a database solely for client config settings (locations, connections etc.) On the other hand, syncing a Blackbery via BES with personal journal and personal contacts were so much easier because the mailfile already is always on the server.

Trusted source could be a fake sender address. To trust sender addresses or domains is risky. Would prefer to move the hidden <right click> -> "show images" option more into the visible focus.

Alternatively, the built-in Notes browser should simply use the current proxy settings of the operating system. This way no more need to deal with proxies in location documents.

Rob, I think no new field types are necessary. The field setting could apply as a filter to the dialog which appears after pressing the addressbook field helper button. Also, there already could be some hidden views in the directory, e.g. already filtering mailable respectively access controlling entries. Dependent from the field setting the field helper button displays the content from the one view or the other).
You already have some control over what should happen when pressing the button (e.g. displaying a custom view instead of the default addressbook view). But to implement this you had to build yourself some custom views into the directory. I believe this better could be out-of-the-box functionality. The goal is that there should appear only entries in the dialog which really are valid choices in the given field context.