I had the issue with not being able to send any invoices.....I posted earlier about how to fix....it's below....in the meantime, all of a sudden I could not send an invoice to just ONE customer via my hotmail webmail account through QB....at a Verizon.net account. Not sure if that verizon.net account has anything to do with it or not, but I can send invoices to my own hotmail account and to another yahoo test account. The message I got was "Unable to send emails due to network connection error" I exported a PDF file of the invoice and emailed that to my ONE client from my hotmail webmail account. I have not found a solution and the moderators keep sending and posting the same cut and paste information about 2 step authentication, gmail, Yahoo mail, making sure you have the latest QB, etc. and none of those solve it. I solved my "unable to send estimates" error by the following...NOTE: Sometimes I got into a loop where the dialog box for "use enhanced security" would not let me enter a new value in the "server" field, and I'd have to start the process over....frustrating.
I went into Edit|Preferences and clicked on Send Forms.
On the My Preferences Tab I went down to my email address under Email IDS
I clicked on the email address and clicked the "Edit" button at the bottom of the window
I unchecked "use enhanced security"
I clicked OK.
It then sent me to my MSN Hotmail access page and allowed me to enter my password.
It told me that Quickbooks Desktop was now connected to my Microsoft Email account and it sent me an email verifying that.
Quickbooks then prompted me to go back in and re-check "use enhanced security".
I then went and tested....sure enough it asked for my email password like it always does once each session.
I entered the password and the estimate was sent.
PROBLEM SOLVED....hope that helps others....
