Mailmerge email only sends some of my emails

[Maxfactor]

I have created a mailmerge to email a document. I have connected to my yahoo server properly and this is confirmed by LibreOffice. But when I start to send, I can see the message begin to que up and some of them get sent out, but then suddenly the send dialog box closes and no more emails are sent. I have done this several times and it seems to send “ABOUT” 20 messages before terminating, even though I have about 40 names in my database. I don’t see any sort of error message - the dialog just closes. One other way I know it doesn’t finish is that I put my own email address at the end of the database and that email is never received. If I have a short list with my own name, that I have confirmed that I do receive that email. I have tested with three different spreadsheets of names and only the spreadsheet with a short list completes correctly. I have tried sending with both a PDF and a microsoft attachment and both have the same failure results.

I have disabled firewall and anti virus.

What would cause the send to terminate prematurely?

I am using Windows 10
Libreoffice 5.2

[robleyd]

Check whether your mail provider has a limitation on the number of mails that can be sent in any given period of time.

[RickyCafe]

I am having the same problem but it is not the e-mail provider as evidenced by the fact that the process works fine with Microsoft Office.