Nice write up of the long drawn out war against spammers and protecting email services from abuse:
https://moderncrypto.org/mail-archive/messaging/2014/000780.html
Written by Mike Hearn, a very smart/savvy ex-Googler
Found via tweet by Matt Cutts:
http://twitter.com/mattcutts/status/508108603253743616
As mentioned in the above article, a large part of this war today is fought by spammers bruce force cracking passwords and otherwise breaking into legitimate email accounts and sending their junk out via a legitimate authorised user.
Don’t less yourself become one of these users who has their email account compromised and abused by spammers wrecking your own reputation and that of the mail server that hosts your email service. Protect yourself now by upgrading your passwords.
All users should use very strong passwords on all their mailboxes. Preferably somewhere between 12 and 20 characters long and comprised of random letters (uppercase and lowercase), numbers and special characters (. , / – = + * etc). More information on creating and maintaining passwords can be found here:
http://www.ecologicalhosting.com/news/password-security-17-05-2013
See also:
24 hours in the life of an email server