Yes, a DMARC rua tag absolutely requires the mailto: prefix. This is a very common point of confusion and one of the most frequent mistakes I see when people set up their DMARC record for the first time. The rua tag is a crucial part of your DMARC policy; it tells receiving mail servers where to send the aggregate reports that give you visibility into your email sending activity. Without these reports, DMARC is much less effective.
The correct syntax for the 'rua' tag
The value you provide for the rua tag isn't just an email address, it's a URI (Uniform Resource Identifier). For email addresses, the proper URI format as defined by internet standards is mailto:address@example.com. Omitting this prefix means the record is not syntactically correct, and mail servers that perform DMARC validation may ignore it.
As pointed out in an article on common DMARC pitfalls, one of the most frequent errors is not including the mailto: prefix. It's a small detail that has a big impact on whether you actually receive your DMARC data.
Let's look at an example. A correct DMARC record with an rua tag would look something like this:
v=DMARC1; p=none; rua=mailto:dmarc-reports@example.com;
An incorrect record would omit the prefix:
v=DMARC1; p=none; rua=dmarc-reports@example.com;
While the second example looks right to a human, a machine parsing it according to the DMARC specification will likely fail to process it correctly.
Why is the 'mailto:' prefix necessary?
The necessity of the mailto: prefix comes down to adhering to technical standards. The DMARC specification (RFC 7489) defines the value for the rua and ruf tags as a "DMARC-URI". This format is designed to be extensible, meaning in the future, reports could potentially be sent to destinations other than email inboxes. By requiring a scheme like mailto:, the record explicitly declares the protocol to be used for delivering the report. This removes ambiguity and ensures that different systems interpret the record consistently.
What happens if you forget it?
Forgetting the mailto: prefix has one simple, but critical, consequence: you will not receive your DMARC aggregate reports. The entire purpose of the rua tag is to collect this data, so making this small error effectively neutralizes your monitoring efforts. The mail servers at places like Google and Microsoft will see your rua tag, determine it's malformed, and simply discard it. They will not attempt to guess your intention and add the prefix for you.
- Always prefix email addresses in rua and ruf tags with mailto:.
- The value is a URI, not just an email address.
- Forgetting the prefix means you will not get DMARC reports.
- This is a strict requirement of the DMARC standard (RFC 7489).
