Fix some README grammar and formatting

README.md

@@ -1,12 +1,18 @@
 # postfix-relay
-Postfix SMTP relay docker image. Useful when wanting to sending email without using an external SMTP server.
+Postfix SMTP relay docker image. Useful for sending email without using an
+external SMTP server.
 
 ## Usage
-`docker pull mwader/postfix-relay` or clone and build it yourself. Default postfix is configured to be an open SMTP relay that rely on docker links for firewalling so be careful to not expose it publicly.
+`docker pull mwader/postfix-relay` or clone and build it yourself. Default
+postfix is configured to be an open relay that rely on docker networking
+for firewalling. So be careful not to expose it publicly.
 
-All postfix configuration options can be set using POSTFIX_* environment variables. See [Dockerfile](Dockerfile) for default configuration. It will work without making any changes but you might want to change `POSTFIX_myhostname`, the FQDN used by 220/HELO.
+All postfix configuration options can be set using POSTFIX_<name> environment
+variables. See [Dockerfile](Dockerfile) for default configuration. It will
+work without making any changes but you might want to set
+`POSTFIX_myhostname`, the FQDN used by 220/HELO.
 
-#### Using docker run 
+#### Using docker run
 ```
 docker run \
 	-e POSTFIX_myhostname=smtp.domain.tld \
@@ -16,12 +22,11 @@ docker run \
 Now run some other container with a link to `smtp` and use it as SMTP server.
 
 #### Using docker-compose
-
 ```
 app:
   links:
     - smtp
-  # some app container config where host "smtp" is used as SMTP server
+  # use hostname "smtp" as SMTP server
 
 smtp:
   image: mwader/postfix-relay
@@ -31,15 +36,21 @@ smtp:
 ```
 
 ## SPF
-
-When sending using your own SMTP server it is probably a very good idea to setup [SPF](https://en.wikipedia.org/wiki/Sender_Policy_Framework) for the domain your sending mail from.
+When sending email using your own SMTP server it is probably a very good idea
+to setup [SPF](https://en.wikipedia.org/wiki/Sender_Policy_Framework) for the
+domain your sending mail from.
 
 ## DKIM
+To enable [DKIM](https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail)
+specifying a white space separated list of domains using `OPENDKIM_DOMAINS`.
+At container start new key pairs for each domain will be generated if not found
+in `/etc/opendkim/keys/<domain>"`. To persist the keys make sure to add a host
+directory volume for `/etc/opendkim/keys`. If your using docker-compose it will
+automatically take care of moving data volumes between container recreates.
 
-To enable [DKIM](https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail) specifying a white space separated list of domains using `OPENDKIM_DOMAINS`. At conatiner start new key pairs for each domain will be generated if not found in `/etc/opendkim/keys/<domain>"`. To persist the keys make sure to add a host directory volume for `/etc/opendkim/keys`. If your using docker-compose it will automatically take care of moving data volumes between container recreates.
-
-DNS records to configure can be found in the container log or by running `docker exec -ti <container> sh -c "cat /etc/opendkim/keys/*/mail.txt"`.
+DNS records to configure can be found in the container log or by running
+`docker exec -ti <container> sh -c "cat /etc/opendkim/keys/*/mail.txt"`.
 
 ## License
-
-postfix-relay is licensed under the MIT license. See [LICENSE](LICENSE) for the full license text.
+postfix-relay is licensed under the MIT license. See [LICENSE](LICENSE) for the
+full license text.