Category: Mac

Mountain Lion Server: Mail Message Size Limit

By default, Mountain Lion Server’s installation of Postfix (the mail server), each email has a default size limit of 10 MB.  That’s generally OK, but to avoid errors and undelivered emails, many people advise increasing the limit.

In order to increase the size limit to 25 MB, open Terminal.  Type in the following command, then press enter.  Once you press enter, you’ll be prompted to enter your administrator password.

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sudo serveradmin settings mail:postfix:message_size_limit = 26214400

Although generally not required, you can restart the mail server.  Do to this, open Terminal and execute the following command:

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sudo postfix reload

Then, open the Server app and toggle the Mail service off and on again.

You’re done.


If you have any questions or trouble with these commands, just comment here and I’ll be happy to offer some assistance.



Mountain Lion Server: Disable Greylisting

Greylisting. Was it ever a good idea?ServerCenter

Well, some say so.  Greylisting (detailed at is a spam prevention technique for mail servers.  The concept is simple:

– When your mail server receives a message from a new sender, the server temporarily rejects the message with a “try again later” or “delay” message.

– Most outgoing mail servers (senders) will indeed try again.  Sometimes this doesn’t occur for a while, though.  15 minutes, 30 minutes, a hour….longer.

– When the message is sent again, it’s cleared and delivered to the user.

Most spammers don’t get this option.  Spammers are smart, though! They know this trick. So, was this ever a good idea?  Maybe.  Is it useful now?  I say no.

Disable Greylisting on Mac OS X Mountain Lion Server

Open Terminal on your server and execute the following command:

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sudo serveradmin settings mail:postfix:greylist_disable = yes

You can restart the Mail server, as needed.


You’re done.  Comment here if you have any challenges using this command.


Mac OS X Server Rejects Mail with No Subject Line

Is Mac OS X Server 10.6 (Snow Leopard) rejecting your e-mail messages which lack a subject line? Mine was, and so does the default setting on Snow Leopard Server.

Here’s a quick fix:

1) First, stop the mail service.

2 Now, you’ll want to edit the header_checks file that’s utilized by postfix.

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sudo nano /etc/postfix/custom_header_checks

3) Next, you’ll see a line which says:

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/^subject: *$/ REJECT empty subject header

Comment out this line by adding a pound sign (#) at the beginning of the line.

4) Once you comment out this line, it should appear as:

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#/^subject: *$/ REJECT empty subject header

5) If you’re using nano or pico to edit the file, click Control+O to write the file. (Save and Exit).

6) Now, restart the Mail service and the server will no longer reject email with no subject line.


Let me know if this solution works for you! Enjoy!

“Lock Desktop” – New Mac OS X App

I’ve uploaded one of my first applications for a Mac. It’s extremely easy to use. The tool allows you to lock your desktop when you’re away from the computer and requires a password when you get back.  This is something you can run on demand, instead of waiting for a screen-saver, or logging off.  Lock Desktop 1.0 even keeps your programs running in the back.  Read more →