Why do messages to certain contacts not appear as read?

• Message Sending
  The message is being sent to the server. If this status lasts for more than a few seconds, there might be a connection problem. In this case, the message will stay in queue and will be sent as soon as the connection has been re-established (on iOS, only when the app is open).
• Message Sent
  The message was successfully delivered to the server, and a push notification was sent to the recipient if necessary.
• Message Delivered
  The message was successfully delivered to the recipient’s device; it has not yet been opened by the recipient, but a push notification was displayed. If the recipient has disabled read receipts, this status is permanent and persists even if the message was read.
• Message Read
  The message has been read by the recipient. If the recipient has disabled read receipts, this status will not be returned.
  
• Voice Message Played (Android)
  The voice message has been played by the recipient. On the sender’s end, the “message read” status (or, if read receipts are disabled, the “message delivered” status) is displayed regardless of whether the recipient has played a voice message or not.
  
• Sending Failed
  The message could not be sent. This can happen, for example, when the network connection is interrupted during a file transfer. On iOS, tap the “Retry” icon next to the message. ()
• / User Agreement/Disagreement
  The recipient agrees/disagrees with your message. (Learn more about the agree/disagree feature here.)

A colored stripe (or the absence thereof) below the title bar indicates the connection status:

• Red: Threema is currently not connected to the server. This is usually due to problems with the Internet connectivity of your phone (e.g., when you have no 3G reception, or if you are connected to a broken Wi-Fi network or to a Wi-Fi hotspot that requires login). Threema will keep trying to establish a connection every 10 seconds.
• Orange: Threema is connecting to the server. A response has been received (i.e., a connection has been established), but the login process has not been completed yet. If this status persists for more than a few seconds, it’s usually due to a slow or unstable Internet connection.
• No stripe: Threema is connected to the server. New messages will appear instantly.

If these symptoms occur, either push notifications aren’t working properly, or there is a problem concerning background activity. In other words, mobile devices (especially Android devices) restrict the app activity in the background after a while. Please follow the troubleshooting instructions for Android (Samsung, Huawei, Xiaomi, Sony, OnePlus, Gigaset, Ulefone Armor, Doogee, etc.) or iOS.

• Android: You can insert emojis via the menu next to the text input field. Third-party emoji keyboards are not necessary.
• iOS: Open your phone’s system settings, tap “General > Keyboard > Keyboards,” and activate the “Emoji” keyboard. After that, you can switch to this keyboard while you’re typing by tapping the globe symbol.
  

On Android (all app versions) and iOS (Threema version 2.9.0 and above), incoming messages can be decrypted in the background and presented along with a preview in the push notification. Push preview must be enabled in Threema settings for the preview to be shown.

If there is no Internet connection immediately after a push notification has been received, it is possible that no preview can be shown.

No preview will be shown on Android if:

• the master key is locked, or
• PIN protection is activated, or
• background data is restricted

Contact Names

On iOS, if there is no Internet connection immediately after a push notification has been received, it is possible that the real contact name cannot be shown.

If the real contact name cannot be shown, the “public nickname” is displayed instead. By default, it assumes the value of the user’s ID, but can be changed anytime. You can ask the sender to use their first name, for example. This will help you recognize the sender of a message.

Problems with sending messages can have different causes. Please proceed as follows:

1. Please send a message to the ID ECHOECHO. If this works and you receive a response, you’re fully able to send and receive messages, and the problem is most likely on the recipient’s side.
2. Make sure that the Threema ID displayed for the contact you want to reach is still actively used by the recipient. The recipient might be using a new ID, in which case messages to the old ID are being misrouted. This can easily be prevented by deleting old IDs and removing duplicate contacts.
3. Maybe your ID has been unintentionally blocked by the recipient. Ask the recipient to check this in your own contact’s details (iOS: Threema > Contacts > Contact details > Block contact (at the very bottom); Android: Threema > Contacts > Tap and hold on the contact > Settings > Deblock contact). Please also make sure that you have not blocked the recipient yourself.

There is a special ID named ECHOECHO that simply echoes back all messages that you send to it. Scan this QR code to verify its key:

Note that in general, QR codes for ID verification should not be sent over the Internet but only scanned from the personal mobile phone of the respective person in order to ensure that there has been no manipulation by third parties.

Messages and files are stored on the servers until they are successfully delivered or until 14 days have elapsed (whichever happens first).

Block Single Users

If you receive unwanted messages (spam, junk messages) from another Threema user, you can block them:

• Android: Open the contact details by tapping the contact’s profile picture. Then, navigate to “Block contact” in the side menu. Alternatively, you can add the contact’s Threema ID to the blacklist in “Threema > Settings > Privacy > Blacklist.”
• iOS: Tap the contact in the contact list and scroll down to the option “Block contact.”

A blocked contact doesn’t see if they are blocked.

Block Unkown

Threema allows you to block messages from unknown users in general. You will find this option in “Threema > Settings > Privacy > Block unknown.”

Please note: When the option “Block unknown” is enabled, you might not receive messages from your friends if you didn’t save their details in your address book or if they didn’t link an email address or phone number to their Threema ID. This could make them believe that the sending of messages isn’t working properly.

Specific contacts can be excluded from your contact list by adjusting “Threema > Settings > Privacy > Exclusion list.”

Everything you send with Threema is encrypted before sending. This can require a high processor load, especially on older devices. We strive to provide both security and performance to all our users independently of their devices, which is why the sending of videos is currently possible within the following limits:

Android: Irrespective of its duration, the video’s file size cannot exceed 100 MB. You can set the video compression in “Threema > Settings > Media.” Increasing the compression allows you to send comparatively long videos.

iOS: Videos in high quality can be up to 24 minutes long; in low quality, videos can be up to 112 minutes long.

Threema transmits messages via the Internet. Aside from Internet connectivity charges (which may vary depending on the mobile network provider), there are no other fees per message.

If you are using Threema behind a Firewall, please make sure that the following TCP ports are open:

• 5222
  
• 443
  

To make Threema Calls, port 3478 or port 53 needs to be open for outgoing UDP STUN/TURN traffic.

To reliably receive push notifications, the following TCP ports need to be open:

• 5223 (Apple)
  
• 5228-5230 (Google)
  

If it happens that it takes a while until the recipient receives your message, either push notifications aren’t working properly on your contact’s phone, or there is a problem concerning background activity. In other words, mobile devices (especially Android devices) restrict the app activity in the background after a while, and the app cannot be reached for calls.

Please ask your contact to follow the troubleshooting instructions for Android (Samsung, Huawei, Xiaomi, Sony, OnePlus, Gigaset, Ulefone Armor, Doogee, etc.) or iOS.