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Many people do not want to install two redundant mail proxies, instead
-they use the mail proxy of their ISP as fall-back. This is simply done
+they use the mail proxy of their ISP as fallback. This is simply done
by adding an additional `MX` Record with a lower priority (higher
number). With the example above this looks like that:
proxmox.com. 22879 IN MX 100 mail.provider.tld.
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-Sure, your provider must accept mails for your domain and forward
-received mails to you. Please note that such setup is not really
-advisable, because spam detection needs to be done by that backup `MX`
-server also, and external servers provided by ISPs usually don't do
-that.
+In such a setup, your provider must accept mails for your domain and
+forward them to you. Please note that this is not advisable, because
+spam detection needs to be done by the backup `MX` server as well, and
+external servers provided by ISPs usually don't.
-You will never lose mails with such a setup, because the sending Mail
+However, you will never lose mails with such a setup, because the sending Mail
Transport Agent (MTA) will simply deliver the mail to the backup
server (mail.provider.tld) if the primary server (mail.proxmox.com) is
not available.
-NOTE: Any resononable mail server retries mail devivery if the target
+NOTE: Any reasonable mail server retries mail delivery if the target
server is not available, i.e. {pmg} stores mail and retries delivery
-for up to one week. So you will not loose mail if you mail server is
+for up to one week. So you will not lose mail if your mail server is
down, even if you run a single server setup.
Anyways, it’s quite simple to set up a high performance load balanced
mail cluster using `MX` records. You just need to define two `MX` records
-with the same priority. I will explain this using a complete example
-to make it clearer.
+with the same priority. Here is a complete example to make it clearer.
First, you need to have at least 2 working {pmg} servers
(mail1.example.com and mail2.example.com) configured as cluster (see
mail2.example.com. 22879 IN A 1.2.3.5
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-Btw, it is always a good idea to add reverse lookup entries (PTR
+It is always a good idea to add reverse lookup entries (PTR
records) for those hosts. Many email systems nowadays reject mails
from hosts without valid PTR records. Then you need to define your `MX`
records:
This is all you need. You will receive mails on both hosts, more or
less load-balanced using round-robin scheduling. If one host fails the
-other is used.
+other one is used.
Other ways
Multiple address records
^^^^^^^^^^^^^^^^^^^^^^^^
-Using several DNS `MX` record is sometime clumsy if you have many
+Using several DNS `MX` records is sometimes clumsy if you have many
domains. It is also possible to use one `MX` record per domain, but
multiple address records:
image::images/screenshot/pmg-gui-cluster-panel.png[]
-You can create a cluster from any existing Proxmox host. All data is
+You can create a cluster from any existing {pmg} host. All data is
preserved.
* make sure you have the right IP configuration
image::images/screenshot/pmg-gui-cluster-join.png[]
-When you add a new node to a cluster (join) all data on that node is
+When you add a new node to a cluster (using `join`) all data on that node is
destroyed. The whole database is initialized with cluster data from
the master.
clustering algorithm, so you just need to reboot the repaired node,
and everything will work again transparently.
-The following scenarios only apply when you really loose the contents
+The following scenarios only apply when you really lose the contents
of the hard disk.