If you've been digging around the source code of the emails Buttondown sends on your behalf — or if you've been scouring the web for information about how to send emails in bulk — you might have come across the term "precedence: bulk."
This is a bit of metadata that tools like Buttondown can add to the emails they send on your behalf. It's a way of telling the email client that the email is part of a bulk send, and that it should be treated as such.
But what does that mean, exactly? And why does it matter?
Depending on what you read, you might come across some folks claiming that setting precedence: bulk will help your emails avoid the spam folder — or might bias clients towards throwing you in the Promotions tab — or might do any number of things.
In reality — and as with many things in the world of email deliverability — the truth is a bit more nuanced. The precedence: bulk header is a bit of a relic from the early days of email, and it's not something that most email clients pay much attention to these days, with one exception:
If you set precedence: bulk, clients like Outlook and Gmail will not send you automatic replies like out-of-office messages. This is really nice: it means that you won't get a flood of auto-replies when you send out a newsletter to a large list.
(And, yes — Buttondown automatically sets precedence: bulk on all emails it sends on your behalf.)
(Still morbidly curious? Check out RFC 3834, which is the standard that defines the precedence header.)