Features

Message edits and deletes

• Support incoming and outgoing edits and deletes: Discord, Mattermost, Slack and Telegram.
• Support only incoming edits: Gitter. (gitter API doesn't support outgoing edits)
• Support only deletes: Matrix.
• Support no deletes or edits: IRC, Rocketchat(NR), Steam(NR), XMPP(NR)

NR = Not researched

Attachment / files handling

The logic is: Public links > Native file upload > External mediaserver > Private links

This means that bridges:

• will receive the "public link" from protocols that have links to files without authentication (Gitter, IRC, Discord)
• that support native file uploads (Discord,Matrix,Mattermost,Slack,Telegram) will receive a uploaded copy of the file from protocols that have links to files with authentication (Matrix, Mattermost, Slack, Telegram)
• that do NOT support native file uploads (Gitter,IRC,Rocketchat,Steam,XMPP) will receive the "public link" from your "external mediaserver" from protocols that have links to files with authentication (Matrix, Mattermost, Slack, Telegram). (If you have configured an "external mediaserver")
• that do NOT support native file uploads (Gitter,IRC,Rocketchat,Steam,XMPP) will receive the "private link" from protocols that have links to files with authentication (Matrix, Mattermost, Slack, Telegram). (If you have not configured an "external mediaserver")

For example if you bridge between slack and discord:

When you upload a file to slack. The link you get from slack needs authentication, so matterbridge downloads this file and reuploads it to the destination bridge Discord (which support native file uploads). If you upload a file to discord, matterbridge will just sent the link to slack (because the discord links are public and don't need authentication)