Many Chinese people now prefer to manage their contacts using a proprietary mobile messaging and social networking application called WeChat
|Other party's action||Result on your side|
|Delete conversation||No immediate effect. If you send further messages, a new conversation is started on the other device, but it still looks like one continuous conversation on yours.|
|Clear chat history||Similar to "Delete conversation" above|
|Delete and Leave (in a group chat)||Deletes their copy of the chat history and removes them from the group. The group continues to exist. (To really shut down a group, an administrator can remove each member from it. Even then, each member continues to keep a copy of the group chat history for the time they were a member, until they delete it themselves or reinstall etc.)|
|Block ||No immediate effect unless you check their Album (Moments), which behaves as if they'd selected "Delete contact" (below). But if you send further messages, you are told "The message is successfully sent but rejected by the receiver" and the other party is told nothing. They can still send you messages. Note also that if you send a "broadcast message" (群發, located under Me / Settings / General / Features for some reason), you are not told which recipients reject it; you must send individual messages to be told.|
|Delete contact ||No immediate effect unless you check their Album (Moments), which will be blank if they've turned off "Public Moments" in the privacy settings (but this could also mean they've seleted "Don't share my moments" with you, or simply haven't ever posted anything for non-Tagged contacts); if they have "Public Moments" turned on then you will see the message "Only 10 posts of this user are visible" (the Chinese version of this message begins "non good-friend" which was lost in translation), and the options to Like or comment on the posts are not displayed (but some versions of WeChat still let you "Like" the album "cover"). Not to be confused with the message "Only 3 days of Moments are viewable" (which happens if they set Settings / Privacy / Set a time limit for Moments viewable by others)---that one applies whether or not you've been deleted, and still lets you comment if not.|
If they deleted you and you try to send further messages outside the Album, you are automatically put back through the process of adding yourself to their contacts: if they've turned on "friend confirmation", you'll see "(Person) has requested friend verification. Please send a friend request to chat" with a link to do it; otherwise your message goes through immediately and they are given the message along with the option to add you. Previous conversations are deleted from their side but not from yours. "Broadcast messages" are silently dropped as above.
Incidentally it may be worth knowing that the Chinese version of "Moments" is, not
|Block and delete contact||Behaves exactly like Delete contact alone, since deleted contacts are also removed from the Blocked List|
|As far as I can tell, these are not actual WeChat options but are colloquial terms for the above 'block' or 'delete' operations, probably carried over from other software. However I have not tried every version on all platforms---there might be variation in terminology between WeChat versions.|
|Report ||No immediate effect. I don't know what happens if an administrator approves the report.|
|Uninstall the WeChat application||No effect. They're just offline until they reinstall. I don't know how long it takes for an unused account to expire.|
|Delete account||Contact is greyed out and marked "Account deleted"; selecting it says "account deleted by other user" and presents a Delete button which, if pressed, also deletes the conversations; otherwise any attempt to send more messages is met with "The other user cannot receive message"|
The size limit for inline videos is just under 14MiB, and the mobile application should be used to introduce these into the WeChat network (i.e. by 'Share' or 'Send' from another mobile application)---at least some versions of the desktop application send videos as "files" that need extra action to view. Attempts to send videos larger than 14MiB on the mobile application get the error "unable to import", although the "say something" caption (if any) is sent anyway.
By comparison, WhatsApp usually compresses inline images to around 250k (with no option to see full size), Telegram scales down to max 1280 pixels per dimension and sends the result as an 87%-quality JPEG (unless uploaded as a file), and LINE can send large JPGs but the recipient must save (to Pictures/LINE) to access resolutions higher than the zoomed-out screen (this screen's "pinch to zoom" does not add more detail), so you'd have to set a reduced DPI to avoid double-bluring.
They therefore put up with their data being sent through Chinese servers (which, apart from anything else, can be slow when you're outside China), with the "vanishing contacts" issue, and with WeChat's limited range of font sizes (especially on high-DPI devices) and limited functionality on the desktop. At least its sound compression ratio is reasonable.
Sometimes they'll accept an alternative installed alongside WeChat for use while they're in the UK. My current recommendation is Telegram Messenger, which is run by a non-profit, can be set to larger fonts, has a good range of desktop clients, etc. But not everyone even understands what it means to install a different application. Some of the older generation I met evidently had it installed by the manufacturer, a shop, or a friend or relative, and don't know what I mean by "install something else". Additionally, some older devices (e.g. iOS 4.x) cannot run recent versions of many applications, so it would be necessary to find an old version and somehow 'side-load' it, or risk an OS replacement.
Disclaimer: The notes on this page are provided in the hope that they are useful, but they are not official instructions and may contain mistakes. Your use of them is at your own risk.