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I am using Linode and have built a LAMP stack. I setup Google Apps (free edition) to handle all incoming mail. I've also setup Google Apps to use DKIM authentication. The problem is when my application sends mail (sign up verification, lost password, etc.) the email is not signed. I do know that the DKIM authentication was setup correctly because when I send mail from Google Apps it is signed as expected.

How do I go about signing application generated emails via Google Apps DKIM authentication?

I am in no way a server admin, so detailed instructions would be very much appreciated.

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Which distribution of linux are you using at linode, and what version? – becomingwisest Oct 16 '12 at 17:52
@becomingwisest I am using Ubuntu 12.04 LTS – user141350 Oct 16 '12 at 20:12
up vote 1 down vote accepted

Can your application send emails using a username and password for smtp? If so, it should be easy to point your application to send via gmail's smtp server. If not, it will probably be best to configure postfix to use a milter to sign the outgoing emails your app sends.

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I am sure my app is capable of it, I just don't know how. Would either of these tutorials be what I am looking for;,…? – user141350 Oct 16 '12 at 20:15
I think either of those tutorials will work. I personally would use the second one because it uses postfix instead of something that is deployed less often. – becomingwisest Oct 16 '12 at 21:48
Will I require an SSL certificate before I can connect to Google's SMTP mail server? – user141350 Oct 17 '12 at 1:31
No you won't need an ssl certificate. – becomingwisest Oct 17 '12 at 2:37
I tried out the second tutorial and it didn't work (typos and what not) but I found this one ( which did the trick. Thank you so much for your help! – user141350 Oct 17 '12 at 18:02

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