I assume this has been asked before but this would be a nice feature especially with people doing 4man fixed content as well now. I played another mmo that implemented this after a add-on became popular for it.

Basically the idea would be having a calendar that opens up showing invites to events on days throughout the month. If someone invited you, you get a small notification where the new mail icon appears. You can go to the social menu and open up calendar. The invite with show the content, brief description and you can respond accept, decline or tentative while selecting the job/role you agree to go on. For a person creating an event it would be similar to the party finder interface. You select the content, party composition and then are able to send invites to friends list, FC or linkshell. If there is fears of spam, it can be restricted Friends list or FC.

I understand there is tools outside game for this like Google calendar or the lodestone but I haven't meet anyone EU who uses the lodestone event calendar and can't see that changing. I know statics will also already have their own scheduling system but the idea of this is to help people do scheduled organised content outside their static with people they know with ease.