

You can find this option for IMAP and Exchange accounts either per folder (right-click>Properties>Offline) or in Menu>Accounts section under sync settings for the whole account (under IMAP and Exchange tabs of the given account). With the download of attachments for offline use eM Client will download the data in the background, so once you actually select to open the file, it will be available.

You can speed up the opening of your attachments if you download them for offline use - by default, eM Client does not do so, so it starts the download once you actually opt to do so. In comparison FairEmail for Android - at a fraction of emClint price - rocks and has a cleaner interface. I believe my two stars are a honest verdict. Some sliders are too tiny and hard to grab.

This double envelope is the de facto standard for certified emails in Italy, and their management is not straightforward. I miss the ability to show "as a single unified message" the emails containing an embedded. I miss email annotations that I used a lot with Eudora. I miss not being able to see name AND email address simply concat together: many persons may have an official and a private email, so I need to view which one at glance, w/o hovering the mouse. The interface is not always intuitive and lacks customization. So my verdict is that emClient is fragile at least. This does not occur on all the other apps on my Mac. Besides that, each (rare) episode of power outage ends always with email databases damaged beyond repair. I live dangerously, since no way is provided to fully disable auto-update popups.

Otherwise this happens, a crash occurs, and I have to spend time to fix. Every month - when the app wakes up to ask for auto-update - I must not miss to say "No". They said that I own a too old MacOS, and updates compatibility is not granted even between minor incremental versions. It installed flawlessly, w/o warnings, corrupted my local email databases and then quit. Few month later (Oct 2021) emClient made a minor update crashing on my iMac. After the trial period I bought in July 2021 the Pro version for Mac.
