Change a Message’s Priority in Mozilla Thunderbird, Netscape, or Mozilla

Not all email is equally time-sensitive. Use the Priority flag to reflect this urgency when you write and send a message in Mozilla Thunderbird, Netscape or Mozilla. Depending on how important a message is to you (or how important you think it should be for the recipient), you can give it a low, normal or high priority. To change the priority of an outgoing message in Netscape or Mozilla:

Add a Priority Button to the Email Composition Toolbar in Mozilla Thunderbird

To add a priority button to the Mozilla Thunderbird message composition toolbar:

The History and Importance of Email Importance Headers

Every email needs at least one recipient so every email has a To: field — and, perhaps, a Cc: field or a Bcc: field. Because you cannot send a message without specifying at least one addressee, these corresponding fields are well-developed in email standards. A message’s importance has, by comparison, never seemed so, well, important. This insignificance led to a proliferation of header fields for the purpose: everyone and their company rolled their own header or at least interpreted an existing header in new ways. So, we have the “Importance:”, “Priority:”, “Urgency:”, “X-MSMail-Priority:” and “X-Priority:” headers and there are possibly more.

What Happens Behind the Scenes When You Select a Message Priority in Mozilla Thunderbird

Mozilla Thunderbird employs and interprets exactly one of these possible headers when you send an email. When you change the priority of a message you are composing in Mozilla Thunderbird, the following header will be changed or added:

X-PriorityTakes the values from 5 to 1 in descending order, 5 for lowest and 1 for highest importance.X-Priority is a non-standard email header; Importance would be a standard header.

Specifically, Mozilla Thunderbird will set the following values for the possible importance choices: With no priority set explicitly, Mozilla Thunderbird will also not include an X-Priority header.