Hello,

I have a database of around 30,000 people I send email to on a regular basis (monthly) they are all customers and have opted-in to receive email updates.

I've done all the usual best practice stuff - made sure reverse DNS is working, SPF records for the sending domain are all in order, included contact details and an unsubscribe link in the body of the email, kept the html/image payload low and included a text only version of the email. But I have a small problem sending *@xtra.co.nz email addresses.

The first few hundred emails get to Xtra recipients fine, then I start getting:

"Nov 21 09:58:32 hostname sm-mta[31774]: pAMKwVJP031772: to=<user@xtra.co.nz>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=129524, relay=mx2.tnz.mail.yahoo.com. [124.108.96.211], dsn=4.0.0, stat=Deferred: 421 4.7.0 [TS01] Messages from <my ip address> temporarily deferred due to user complaints - 4.16.55.1; see http://postmaster.yahoo.com/421-ts01.html"

Retrying the send to the affected email addresses four or more hours later does seem to work about 50% of the time. I've filled out the contact forms a few times, but get nothing other than the standard canned responses.

No issues sending email to any other ISP's or email providers.

Anyone have any tips?

Cheers.