QQ

QQ is an instant messaging service that includes email, social groups and games, and online chat products, headquartered in China as part of Tencent. Email delivery can be unpredicatable for non-Chinese businesses or when sending through mailservers outside of China. For the most insight, register your Return-Path domain with QQ's Postmaster site to directly monitor delivery and respond to any spam complaints.

Codes

501 · 550

501
501 Bad address syntax. http://service.exmail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000730
550
550 Mail is rejected by recipients

You are on this recipient's personal blacklist or your message has been rejected because of a filter they've created.

550 Mailbox unavailable or access denied

The recipient you're trying to send to is receiving a large number of emails in a short period of time. To avoid malicious attacks, sending to this recipient is temporarily prohibited.

550 Mailbox not found. http://service.exmail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000728

This recipient does not exist.

550 Mail content denied. http://service.exmail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000726

The content of the email was suspected of being sent in large numbers and was reported by a lot of users as spam.

550 Sender frequency limited. http://service.exmail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000723

The sender 's sending frequency exceeded the limit. The amount of time that further mail is prohibited from being delivered depends on the limit exceeded. (for example, sender, hourly, daily). These limits are not disclosed.

550 Suspected spam sender.

Suspected of spam/a large amount of spam was sent from the domain name or mail operator.

550 DMARC check failed http://service.mail.qq.com/cgi-bin/help?subtype=1&&no=1001508&&id=16.

The sent message failed the DMARC policy for the sending domain. If the sending domain has a reject policy set for DMARC, the message must pass DKIM or have SPF aligned to the domain with a custom Return-Path. To resolve this, you'll need to contact your email service provider to see how to send a message that passes DMARC support.