In Lotus Notes I have a bunch of messages from a certain sender I would like to move them to a certain folder or delete them. I created a rule but that doesn't apply to the messages I already received. Is there a way I can select all messages from a certain sender and move them to a folder or delete them? I tried sorting by "Who" but I can't hold down shift and select multiple messages.
I'm using Notes 8.5. I'm not sure what you mean by "...I can't hold down shift...". I just discovered this following method after reading your question, after searching for an answer to the same desired action.
Regarding the answers from rhsatrhs, I've been using their first method for years, works great, and is almost as fast as it can be done. What usually happens, though, is you will also put checks next to a few more e-mails below the desired ones, and then you de-select those, which is no big deal. If you scroll/mark about 10 at a time, then that's not as much of a problem. My method, which surprised me that it worked, is just a little faster, because you can scroll faster, and it will only mark the desired e-mails.
Using their 2nd method, however, I can't get any subsequent marks to appear. And for me the definition of "select" means to have that rectangle-line around an e-mail (whether bold or not), and only one can be "selected". I think by "select" they meant mark, or select and mark. In any case, using 8.5, if I both select and mark on the top desired e-mail, then hold Shift and scroll down, none of the other e-mails get marked...all that happens is the window scrolls down.
Sort the view by "Who".
The procedure for selecting multiple messages may be different depending on the version and settings of your Notes client. If these methods don't work for you, please post more information about the version of Notes that you are using.