550-5.7.1 "unsolicited mail"
Until a few weeks ago, I was able to send email mostly anywhere using my local postfix. To me that's the most convenient configuration because I frequently switch networks and I don't like to change my SMTP server every time. So I configured postfix on my laptop and I'm using "localhost" as my SMTP server.
But suddenly, a few popular email servers such as GMail or Yahoo now seem to reject my email with this message:
<email@example.com>: host gmail-smtp-in.l.google.com[188.8.131.52] said: 550-5.7.1 [184.108.40.206] Our system has detected an unusual amount of unsolicited 550-5.7.1 mail originating from your IP address. To protect our 550-5.7.1 users from spam, mail sent from your IP address has been 550-5.7.1 rejected. Please visit 550-5.7.1 http://www.google.com/mail/help/bulk_mail.html to review 550 5.7.1 our Bulk Email Senders Guidelines. u1si8404313uge (in reply to end of DATA command)
Err, what should I do here? I'm pretty sure that no SPAM has been sent from my IP. What's "unsolicited mail" anyway? Do I need to ask one to solicit an email from me so I am able to write him? :-) This stuff is quite annoying... Like any security restrictions, SPAM filters affect legitimate use as well.
I'm now forced to login to GMail when I want to send a message to someone at GMail, which kind of sucks..