This guide helps you better understand the peculiarities that may arise in the display of emails when using various messaging applications and Infomaniak Mail apps.

Preamble

• It can happen that inconsistencies occur in the display of a list of emails contained within a folder (example: the Sent folder) Sent Messages) and that the messages sorted and considered as the most recent by one device will not be the same as those displayed when using another tool.

Understanding Unique Identifiers (UID)

UIDs (Unique Identifiers) are unique identifiers assigned to each message in an IMAP mailbox. They are used to uniquely identify each message, regardless of changes made to folders or the messages themselves. UIDs are particularly useful for managing and synchronizing emails across multiple IMAP email clients/software:

• Each email is assigned a unique UID at the time of its creation in a mailbox; this UID does not change as long as the email exists, even if its content or metadata is modified.
• UIDs are typically sequential, which means that more recent messages generally have higher UIDs.
• During email synchronization, IMAP email software/clients can use UIDs to determine which messages are new, modified, or deleted since the last synchronization; this allows for efficient email management without having to download and compare all messages.
• Depending on the tool used, to display them in the order they were received, messages can be sorted by their receipt date or by UID.

Do not confuse with:

• Message Sequence Number (used for temporary operations based on the current position of the messages)…
• Message-ID (RFC 5322) (used to uniquely identify messages across different servers and email clients)…
• X-Message-Id (server-specific and used for internal tracking purposes)…
• Thread-Index and Thread-Topic (used by Microsoft applications for tracking conversation threads)…
• GMail Unique Identifiers (specifically used by Gmail to manage messages and conversation threads)…

IMAP applications and Infomaniak Mail app

The issue may appear in this form at the server command level:

758 - date.sent: 2017-10-11 23:15:26 (+0100)
757 - date.sent: 2017-10-11 15:00:55 (+0100)
756 - date.sent: 2017-10-11 14:39:28 (+0100)
(...)
742 - date.sent: 2018-01-17 00:40:21 (+0000)
741 - date.sent: 2018-01-17 00:30:33 (+0000)
740 - date.sent: 2018-01-17 00:26:07 (+0000)
(...)
51 - date.sent: 2022-10-07 16:39:16 (+0100)
50 - date.sent: 2023-06-13 10:15:00 (+0100)
49 - date.sent: 2023-06-07 12:11:35 (+0100)

Here, it is observed that emails from 2017 have a higher UID (758, 757, ...) than emails from 2023, which are more recent. The UIDs must have been reassigned for some reason or another over the course of this email account's existence (moves, copies, imports, etc.).

Depending on how the email tool sorts messages, an email from 2017 may appear among recent messages while an email from 2018 will not be loaded immediately. This is particularly true for Mail Infomaniak which loads emails in series based on the UID (this is subject to change).

Therefore, to resolve any inconsistencies, it is recommended to use an IMAP email software/client like Thunderbird on a computer, which will allow you to quickly and efficiently sort all the messages in a specific folder, based on the email date, as the application will display all the messages present on the Infomaniak server.