I'm not sure I understand why MassMessage needs modification here. This seems like a purely content issue. Is "~~~~~" inadequate? Or "~~~~" for that matter?

"~~~~~" is inadequate when people forget to add it, or when they sign the message and then add a "P.S." or other content after it.

As an example of "other content", consider the common form of e-mail messages:

Here's the material I promised you.  

<Signature> 

Long message follows signature.

Unless MassMessage's design goal is "screw up bot-archived pages whenever someone inexperienced or distracted uses it", then I think this would be helpful.

(In reply to WhatamIdoing from comment #2)

"~~~~~" is inadequate when people forget to add it, or when they sign the
message and then add a "P.S." or other content after it.

How are people forgetting when MassMessage specifically warns you if you're missing a timestamp? Is the check not working in all cases?

As an example of "other content", consider the common form of e-mail
messages:

Here's the material I promised you.  

<Signature> 

Long message follows signature.

That should work perfectly fine with standard archive bots that use a regex for timestamps anywhere in the thread.

Unless MassMessage's design goal is "screw up bot-archived pages whenever
someone inexperienced or distracted uses it", then I think this would be
helpful.

I don't think anyone said that or implied that.

In T70513#721443, @Legoktm wrote:

That should work perfectly fine with standard archive bots that use a regex for timestamps anywhere in the thread.

But not for those that look only at the very end of the thread.

In T70513#1458388, @Whatamidoing-WMF wrote:

But not for those that look only at the very end of the thread.

Which ones are those?

Is this still needed? Given the warning about not including a timestamp, I'm not sure its an issue