Stop msgbox OK closing text input - vba

Question

Stressed out manager trying to fix a problem in our organisational CRM.
We have a macro set up to send 'ad hoc' text messages to clients. The character limit for the text input is 160, and if you exceed that, a msgbox pops up to tell you to reduce your text by x characters.
When you hit OK, it then kills the entire input box (so you have to re-type a new shorter version of your original message).
How can I set it up so that if you exceed the character limit, it tells you and then gives you the opportunity to go back and delete a few characters?
This is the portion of code I think is relevant:
set msgEntryDlg = CreateDialog("Adhoc SMS")
set msgTxtCtl = msgEntryDlg.AddControl("SMS Message: ",2, "")
if NOT msgEntryDlg.Execute then
Msgbox "Message cancelled!"
Exit sub
end if
mail_message = msgTxtCtl.Text
mail_message = " " + mail_message
If Len(mail_message) < 1 Then
MsgBox "Message was empty, please enter a message!"
Exit Sub
End If
If Len(mail_message) > 160 Then
MsgBox "Message is too long, please reduce by " & (len(mail_message) - 160) & " characters.",4112
Exit Sub
End If
I think it's something to do with a loop ... but I am clueless!
Thanks in advance.

Answer 1

Untested, but I believe you're looking for something like this:
Dim success As Boolean
Do
Set msgEntryDlg = CreateDialog("Adhoc SMS")
Set msgTxtCtl = msgEntryDlg.AddControl("SMS Message: ", 2, "")
If Not msgEntryDlg.Execute Then
MsgBox "Message cancelled!"
Exit Do
End If
mail_message = msgTxtCtl.Text
mail_message = " " + mail_message
If Len(mail_message) < 1 Then
MsgBox "Message was empty, please enter a message!"
End If
If Len(mail_message) > 160 Then
MsgBox "Message is too long, please reduce by " & (Len(mail_message) - 160) & " characters.", 4112
End If
success = True
Loop Until success
If you need to repeat an action until a condition is met, check for the condition at the end of each loop. Note that the cancellation exits the Do, not the Sub.