Apparently the Google SMTP server has two requirements:
1.) You must use TLS encryption. According to the log of your latest attempt, you've managed to solve this. Good.
2.) You must present an username and password to the Google server before it allows you to send mail through it. This is why your latest attempt is failing.
Google is actually trying to help you:
050 530-5.5.1 Authentication Required. Learn more at
050 530 5.5.1 http://support.google.com/mail/bin/answer.py?answer=14257
Unfortunately, the advice is written mainly for desktop users, and is not too useful for configuring Sendmail.
The standard documentation for Sendmail is the O'Reilly book Sendmail. For version 8.13.3, you'll want the 4th edition of the book (or if a newer edition exists, that might be even better). I really recommend this book for anyone who needs to really understand Sendmail.
(It's a very big book, but don't worry - more than half of the book is configuration item reference: use the first chapters and the Table of Contents to find the configuration items you need and ignore the rest.)
Chapter 5.1.5 of Sendmail, 4th edition is about SMTP AUTH, which is the authentication mechanism Google wants you to use. It says the username and password should be stored in either /etc/mail/access or /etc/mail/authinfo depending on the options chosen when building the Sendmail configuration file (= whether FEATURE(`authinfo') was included in the .mc that controls the building of the configuration file or not).
The necessary configuration line would be like:
AuthInfo:smtp.gmail.com "U:GoogleUser" "P:GooglePassword"
Of course, you must replace "GoogleUser" and "GooglePassword" with the actual username & password you use to access Google with.
Both /etc/mail/access and /etc/mail/authinfo are source files for creating the actual access database or authinfo database: just editing the files (or creating them if they don't already exist) is probably not enough. You must also create the actual database file using the makemap command.
To create/update the access.db file, you should do this:
cd /etc/mail
makemap hash access.db < access
Likewise, to create the authinfo.db file (if configured), you should do this:
cd /etc/mail
makemap hash authinfo.db < authinfo
You should first try putting the AuthInfo line to /etc/mail/access (create it if it does not already exist) and creating the access.db file; then restart Sendmail and try to send some messages.
If it does not work, remove the AuthInfo line from /etc/mail/access and put it into /etc/mail/authinfo, then create the authinfo.db file and try again.
Your previous test messages are probably stored into the local email queue directory on your server (/var/spool/mqueue): run mailq to display the mail queue in a more readable form. Once you get the authentication to work, all the queued test messages may be sent to smtp.google.com... so you might want to clear the /var/spool/mqueue directory first, to avoid flooding your mailbox.
MK
