I have been using Flickr for a long time and it seems to work well for posting on forums. 1 TB of photos free. It's part of Yahoo and I've had a Yahoo email address since the 90s. Hardly ever use the email any more, but love Flickr.
https://www.flickr.com/
I usually edit out some of the link when I post, but here is the standard photo sharing link as "BB Code" set to 800x450 resolution:
2017-10-22_07-56-19 by
Jon Russell, on Flickr
There are a lots of options for sharing, such as BB code, embed, direct link, sharing a selection, or folder, etc.
