This guide will help you better understand the specific issues that may arise when displaying emails when using different email applications and Infomaniak's Mail apps.

Introduction

• It may happen that inconsistencies occur when displaying a list of emails within a folder (e.g., the Sent Messages folder), and the messages sorted and considered the most recent by one device are not the same as those displayed when using another tool.

Understanding Unique Identifiers (UIDs)

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 the folders or the messages themselves. UIDs are particularly useful for managing and synchronizing emails across multiple IMAP email clients:

• Each email is assigned a unique UID when it is created 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, meaning that newer messages typically have higher UIDs.
• When synchronizing emails, IMAP email clients can use UIDs to determine which messages are new, modified, or deleted since the last synchronization; this enables 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 date of receipt 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 software/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)...

IMAP applications and the 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, we observe that emails dating from 2017 have a higher UID (758, 757, ...) than emails with a more recent date in 2023. The UIDs must have been reassigned for one reason or another during the lifetime of this email account (moves, copies, imports, etc.).

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

Therefore, to resolve any potential inconsistencies, it is recommended to use an IMAP email client such as Thunderbird on a computer. This 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.