Telegram is a good messenger platform and relatively secure. Run out of Dubai by Russians. Not open source. Does let you choose end to end encryption.

Benefits

• Not controlled by the Western establishment
• Operates out of Dubai and run by Russians
• Good end to end encryption when you enable it for direct messages
• Excellent and fine grained handling of groups messages
• Good for voice calls

Drawbacks

• Operates out of Western-influenced Dubai and run by Russians
• End to end encryption not automatic and doesn't apply to groups
• Not open source. Anything could be happening inside
• When left on default settings, group handling prone to filling your phone up and spam group adds.

Groups

Telegrams best feature is its group handling and range of groups on offer. For many users this is the main reason to use this messenger system. But a major drawback of the system is the default Telegram settings cause it to automatically download and retain a large number of media files, eventually causing the phone to become unusable. This behaviour can be corrected, below, as is the problem of being automatically added to groups.

Preventing and expiring downloads

If you are a member of Telegram groups, it necessary to apply these settings to prevent Telegram making your phone unusable through excessive downloads. It is not uncommon for a member of a Telegram group to unthinkingly post a video a quarter of a gigabyte in size and most people are initially aware of the settings needed to mitigate this.

Click on the settings bars in the top right corner

Click Settings

Click Data and Storage

Turn off all of these and the ones below, then click Storage Usage

Turn these off too and delete all cloud drafts

Set media self-expiry time, then clear cache and local database

Disabling automatic addition to groups

Once you are a member of a group it is likely that some of the members will be bot accounts that will then add you to groups of their own, as a type of spam and often with criminal intent. You should configure Telegram to only allow group adds from your contact list, and from there it is possible to restrict further if one of your contacts forms the annoying habit of adding you without permission too.

Click on the settings bars in the top right corner

Click Settings

Click Privacy and Security

Click Groups

Ensure "My Contacts" is selected. If one of your contacts adds you to unwanted groups, add them to the Never Allow list below

Doing these things greatly enhances Telegram usability and is worth telling all users to do, especially the less technical and new users. You can show them this page.