My messaging habits have roots in the BBS days when ASCII text was all we could publish on telephone/modem based networks, like Fidonet, Synchronet, etc. The features were quite limited compared to today's ability to web together posts integrating audio-visual objects and links to even more of such posts. The problem with external hosts is when they fail it defeats having those internet features, that when local hosting comes handy but at a cost.
I propose asking the forum software author to consider an addition meant to manage both internal and external picture links simultaneously by combining them, in order to strengthen the system instead of dividing damage control - which i view as an enormous cost in terms of man-hours at multiple individual user levels, assuming i'd have the permission level to correct all broken links in the 1st place.
A host manager feature would centralize easy corrective counter-measures, for example presently my pictures posted on PostImages.Org are missing though there's a backup with the .CC domain - which is still useless at the moment because i'm not going to invest days if not weeks searching for broken links and possible updates i just can't use anyway...
The loss ain't trivial, it is immense and most demotivating. What i suggest is to develop a sturdier illustration system where originals are kept locally while external servers contribute with their bandwidth until broken and then replaced with the alternative copy. Or even better, multiple-source copies until falling back to the local original...
Doing so would imply the creation of an additional dialog window when posting pictures, automatically asking for optional sources to supplement the local host, not replace it despite damaging consequences in case of failure. When there's place for 2 why not 3, or 4?... So there shall be a pile of possible external hosts to try before finally resorting to local hosting, if desirable.
It may never happen but that's still a more logical/productive solution to manage the problem globally IMO.
Good day, have fun!!