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

Preamble

• It may happen that inconsistencies occur in the display of a list of emails contained in a folder (example: the Sent folder) 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. Sent Messages)

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 messages themselves. UIDs are particularly useful for managing and synchronizing emails across multiple IMAP email software/clients:

• Each email is assigned a unique UID at the time of its creation in a mailbox; this UID never changes in principle as long as the email exists, even if its content or metadata is modified.
• UIDs are generally sequential, which means that more recent messages have higher UIDs in principle.
• 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 in which they were received, messages can be sorted by their reception date or by UID.

Not to be confused with:

• Message Sequence Number (used for temporary operations based on the current position of messages)...
• Message-ID (RFC 5322) (used to uniquely identify messages across different servers and email software/clients)...
• X-Message-Id (server-specific and used for internal tracking needs)...
• Thread-Index and Thread-Topic (used by Microsoft applications to track conversation threads)...
• GMail Unique Identifiers (used specifically by Gmail to manage messages and discussion 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 can be seen that emails from 2017 have a UID (758, 757, ...) higher than emails from 2023. UIDs must have been reassigned for one reason or another during the existence of this entire email account (moves, copies, imports, etc.).

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

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