eM Client supports server-side conversation synchronization for Google and Exchange servers, as well as IMAP servers that implement the relevant RFC extension, which provides information about which messages belong together.

For accounts where this data is not available, eM Client uses its internal conversation logic, which relies on message headers. The main factors considered are:

• the same base subject

• sender and recipients

• Message-ID, References, and In-Reply-To

The more complete the context, the more accurate the conversation grouping. Note that during initial synchronization, some messages may lack sufficient information, so conversations may not be grouped optimally until synchronization is complete.