Why do I receive "Email hasn’t been sent.Double check your info and try again" when trying to send an invoice to someone I had previously sent one to?

One possible reason you're unable to send an invoice to a customer you've invoiced previously is that your browser has accumulated too many cached files, pottsville. Let's work together and troubleshoot this so you can complete your task and manage your income transactions accordingly.

QuickBooks uses the browser's cache to run faster. Thus, you'll have to clear or remove outdated ones to prevent potential viewing and performance issues with QuickBooks Self-Employed (QBSE).

Start troubleshooting by pulling up your account using a private browser (incognito). Here's how:

• Press Ctrl + Shift + N (Google Chrome)
• Ctrl + Shift + P (Firefox)
• Control + Option + P (Safari)

Once signed in, go to the Invoices menu to create and send an invoice.

If you're able to do so, return to your default browser and clear its cache

 (The article focuses on QuickBooks Online but is also relevant to QBSE). After that, restart your browser and log back into your QBSE account to refresh the system.

However, if this matter continues, I'd recommend clicking the browser's Refresh icon (please see the screenshot below) or using other supported browsers. 

Furthermore, would you like to customize your invoices and set up online payments (if you haven't already)? Please feel free to check out this article (Customize your invoice and Turn on payments drop-down) for the complete guide: Invoices in QuickBooks Self-Employed.

Keep me posted in the comments if you have other concerns about sending and managing invoices in QBSE. I'll gladly help.