Limits on sending emails are imposed by your email provider. The limits may be x number of emails per hour or per day etc. You would need to be clear on what is allowed. For example: https://uk.help.yahoo.com/kb/mail-for-desktop/limits-sending-email-yahoo-mail-sln3353.html https://help.smallbusiness.yahoo.net/s/article/SLN17518 Thunderbird seems to have a limit per email if you enter each email address separately approx 60. http://kb.mozillazine.org/Limits_%28Thunderbird%29 Thunderbird has the ability to create 'Mailing Lists'. This is one identical email sent to a list, you would have to ensure it is sent Bcc. https://support.mozilla.org/en-US/kb/how-create-and-use-mailing-lists-thunderbird You can use an addon called 'Mail Merge' which facilitates sending more personalised email. One email per person so it uses the TO field. * https://addons.thunderbird.net/en-US/thunderbird/addon/mail-merge/ If you are using a third party Mass Mail server then you need to make sure the recipient is aware of this as it could conflict with data protection EU law. This is because they state they can scan any emails you send to check all is correct - no spamming and no abuse etc. It also means they have access to the email addresses contained therein and your recipients may not agree to that. Always worth read the T's & C's if using a mass emailing server.

Thank you so much for your time and the trouble you wen to on my behalf. Errol.