postfix: fix message size limits (#1061)

The message size limit was reduced in c8728eab from the postfix
default [1] of 10,240,000B = 10,000kiB = ~10MiB to only
1,048,576B = 1MiB. And the documentation claims that this would be 10MiB
instead of 1MiB.

Restore the old behaviour as default and fix the documentation as well.

[1]: http://www.postfix.org/postconf.5.html

.env.dist

@@ -108,7 +108,7 @@ POSTFIX_MAILBOX_SIZE_LIMIT=
 
 # Set the message size limit for all users. If set to zero, the size will be unlimited (not recommended!)
 #
-# empty => 1048576 (10 MB)
+# empty => 10240000 (~10 MB)
 POSTFIX_MESSAGE_SIZE_LIMIT=
 
 # Enables a report being sent (created by pflogsumm) on a regular basis.

README.md

@@ -314,7 +314,7 @@ Set the mailbox size limit for all users. If set to zero, the size will be unlim
 
 Set the message size limit for all users. If set to zero, the size will be unlimited (not recommended!)
 
-- **empty** => 1048576 (10 MB)
+- **empty** => 10240000 (~10 MB)
 
 ##### ENABLE_MANAGESIEVE
 

target/start-mailserver.sh

@@ -19,7 +19,7 @@ DEFAULT_VARS["ENABLE_POSTGREY"]="${ENABLE_POSTGREY:="0"}"
 DEFAULT_VARS["POSTGREY_DELAY"]="${POSTGREY_DELAY:="300"}"
 DEFAULT_VARS["POSTGREY_MAX_AGE"]="${POSTGREY_MAX_AGE:="35"}"
 DEFAULT_VARS["POSTGREY_TEXT"]="${POSTGREY_TEXT:="Delayed by postgrey"}"
-DEFAULT_VARS["POSTFIX_MESSAGE_SIZE_LIMIT"]="${POSTFIX_MESSAGE_SIZE_LIMIT:="1048576"}"  # 10 MB by default
+DEFAULT_VARS["POSTFIX_MESSAGE_SIZE_LIMIT"]="${POSTFIX_MESSAGE_SIZE_LIMIT:="10240000"}"  # ~10 MB by default
 DEFAULT_VARS["POSTFIX_MAILBOX_SIZE_LIMIT"]="${POSTFIX_MAILBOX_SIZE_LIMIT:="0"}"        # no limit by default
 DEFAULT_VARS["ENABLE_SASLAUTHD"]="${ENABLE_SASLAUTHD:="0"}"
 DEFAULT_VARS["SMTP_ONLY"]="${SMTP_ONLY:="0"}"