Hi All,

So I am a web developer working for a small start up that needs a reliable email service, other than required maintenance the server needs to be available absolutely all the time, i know this may not be an easy solution or even the best value for money but the powers that be have asked, and i am hoping to find a solution that is suitable.

Our current solution runs citadel on a raspberry pi so is not very powerful but for the first few months this has not been a problem, however we are moving up to AWS in a month and as such to provide redundancy for the web server software we will have multiple running machines.

My current idea is to use the web servers to also host the email server software; however, if, like the web servers, we were to use a round robin DNS approach i am aware that each server would have less than the full set of emails stored. I am also aware that most SMTP MTAs store any un-sendable mail until the host is available again or a set amount of time has passed - so short times, minutes preferably seconds of downtime is not a problem. The problem i have is that how do the clients access emails if the server is down, unless there is a second fully-capable server, and if there is a fully capable server what software would you recommend? and how would you recommend it be implemented?

PS: calendars, contacts are optional, but free and available on debian is a must

thanks and sorry for the amount of text,

-allw

Did you see http://www.citadel.org/doku.php/faq:...standby_server ?

sorry, my fault in not saying, citadel is okay but due to having to install something over the top of it to look decent i was looking for something like postfix MTA and dovecot IMAPd but i have no idea how to set these up redundantly. then over the top of this would go SoGo to handle all the clients, this is far easier to install redundantly. ideally we are looking for active:active and fully replicated