Email cluster, multiserver

[priest666]

Hi.
I was reviewing the documentation regarding custering email accounts, but I need some clarification.

Asumption: Server A, B, C -> DA based webserver/sql server (no emails should be stored here), Server D -> DA based server, used for emails only
Does one click RC login (SSO) work correctly from servers A, B, C or user has to log in to DA on server D?
If user has to log in to server D, what happens if he changes password there?
Where user should set autoresponders, vacation messages, spamassasin rules? On A, B, C servers or on server D?
How does local delivery (lmtp) work if an email is sent using server A, B, C?
Should any email options on servers A, B, C should be disabled, as they are managed on server D? If so, what's the best option to do it?
Do you have any real life examples of email clustering?
Thanks!

 

[mxroute]

These are the articles that reference behavior similar to what you're talking about, at least in relation to the email part:

Version 1.53.1 | Directadmin Docs

DirectAdmin Knowledge Base

www.directadmin.com

Version 1.48.0 | Directadmin Docs

DirectAdmin Knowledge Base

www.directadmin.com

But those functions don't operate in exactly the way I think you're describing it, as they don't seem to reference the idea of the primary box having no email function. So if you achieve the setup you've described, the answers are going to be relative to your work. For example, if you disable email on A, B, and C but users log in to DA there then the one click webmail may fail. But then you could probably alter the roundcube config and that may fix it. Perhaps by pointing it's IMAP/SMTP away from localhost. Or maybe you'd just proxy Dovecot from those servers to D so everything looks like it works on localhost while delegating it.

There's no best way to do what you describe there's just going to be your way. I don't know how many others are going to such an extent, given that it'll increase overhead significantly and probably gain a maximum of 1% (likely less) uptime.