Introduced as a new service since core 94, the IPFire distribution now has an inbuild mailsystem. This System is known as DMA (Dragonfly Mail Agent). It is lightweight and not as complex as Postfix which can be installed as addon.
DMA has a few Advantages over SendEmail because it has some features like bouncemails, a spool directory and logging options. On the other hand it is not as feature rich as postfix but it is easy to use and configure.
DMA can simply be enabled with settings like the smarthost over which mails will be send, an authentication and a systemwide sender and receiver of the mails.
Addons can use the mailsystem to send emails with attachments like WIO or squid-accounting.
Squid-accounting from version > 1.0.4 will only use DMA as mailsystem! If you are using a IPFire Version prior version core 94, the addon squid-accounting > 1.0.4 will NOT WORK.