Search code examples
emailimap

Is the MODSEQ value of an email unique to the entire mail account?

As far as I can see in the IMAP RFC, it appears to say that a MODSEQ value is unique to a folder and will never be repeated unless UIDValidity changes. However, I can't see it saying anything about the account as a whole, rather just folders.

My question is, can I use an emails MODSEQ value as a unique value across the entire inbox, or need I define my own unique value, likely something similar to:

let uid = path + MODSEQ
Solution

  • There are no guarantee about uniqueness across folders. This is because some servers don't know much about other folders than the ones they have open at the moment, and it was considered important to make MODSEQ easy to implement for servers.

    Yes, you need your own uniqueness value.