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{{One source|date=June 2024}}
{{Verifiability|date=December 2021}}
The term '''Mail Hub''' is used to denote an [[Message transfer agent|MTA]] (message transfer agent) or system of MTAs used to route email but not act as a mail server (having no end-user email store) since there is no [[Mail User Agent|MUA]] (mail user agent) access. Examples could include dedicated anti-SPAM appliances, anti-virus engines running on dedicated hardware, email gateways and so forth.
== DNS Based Mail Hub ==
A first example for a '''Mail Hub''' consisting of a network of MTAs would be that of a typical small-to-medium size [[Internet service provider]] (ISP), or for a [[FOSS]] corporate mail system. This solution is very good for developing nation ISPs and NGOs. As well as any other low-budget but high availability mail system needs. This is mostly due to not using expensive [[Network level switch]]es and hardware.
Simple [[Domain name system|DNS]] MX record based '''Mail Hub''' cluster with parallelism and front-end failover and load balancing is illustrated in the following diagram:
[[Image:RAIS-Mail.jpg]]
The servers would be all [[Linux]] [[x86]] servers with low cost [[SATA]] or [[Parallel ATA|PATA]] hard disk storage. The front-end servers would most likely run [[Postfix (software)|Postfix]] with [[Spamassassin]] and [[ClamAV]]. This [[Redundant Array of Inexpensive Servers|RAIS]] server [[Cluster (computing)|Cluster]] would then overcome the problem with [[Perl]] based [[Spamassassin]] being too CPU and memory hungry for low cost servers. The solution presented here is based on all [[GPL]] [[FOSS]] free software, but of course there are alternative configurations using other free or non-free software.
== References ==
Mail Clustering, [http://ws.edu.isoc.org/workshops/2005/pre-SANOG-VI/bc/mail/clustering.htm], ISOC, 2005.
[[Category:Email]]
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