Almost all open source communities use an electronic mail list for discussions. These lists are sometimes managed through online services such as Google Groups, but are often managed through private installations of list management software such as MailMan, which provide subscriber management, bounce control, and web-accessible archiving.

Surprisingly, there is a significant variation from community to community in terms of list ettiquite and even the amount of participation on lists.

Some communities use newsgroups or forums in place of mailing lists, but these are usually gatewayed to an e-mail list -- for example, Mozilla uses newsgroups extensively, but many of the Mozilla newsgroup participants actually access the newsgroups as mail.

An open-source participant subscribed to several lists in multiple communities can easily receive thousands of messages a day. For this reason, many people choose to use a separate mailbox (such as a Gmail account) or filtering rules to keep their mail under control.