I encountered a headache recently. We have over 3800 qq.com in our database. When we send 10 qq.com emails, the deliery rate is 100%, when we sent 20, it will become 75%, if we sent to 100, it will be around 47%. It seems if we sent to too many qq.com emails at one time, the qq.com email server will block our email. The Marketo Supports said the cause of the bounces is that we are sending too many emails, too quickly.
550 Connection frequency limited. http://service.mail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000722
It's impossible for me to split the list to 380 groups and send 380 times in order to get all these people delivered. Have you ever encountered the similar issue before?
I'm all ears to your suggestions.
Many thanks in adance.
It's not so much "at one time" -- rate limits aren't just about concurrent connections but about the number of connections over a certain time interval, like per minute and/or per hour.
Anyway, Marketo doesn't offer a built-in feature to throttle sends at this level of granularity. You can gateway some Marketo sends through a self-hosted server which has throttling applied, though this is a heavily technical task.
Given the increased focus on ABM activity, this is more important than ever to be able to configure "throttle" settings when sending to a single domain:
If you have a dedicated IP address you can file a Support ticket to see if our Deliverability team has any options to help. I believe they can assist in some whitelisting options.