I had a similar problem trying to use Gmail to send photos on my PC. Here's what worked for me.
Go to "Accounts.Google.com"
On the left side of the page, click "Security"
Then, "Signing into Google"
Then, "2-Step Verification" and follow the prompts.
Return to the Security menu.
Look for "Less Secure Apps" section and ensure that it is selected "ON".
IMPORTANT-Review the associated security risks with selecting this option to ON. Consider turning it back OFF when you are done uploading.
(BTW, the setting for "Less Secure Apps" will only appear if 2-Factor Authentication is already turned OFF)
On the PM application, when you click "File" and then "Send Photos via Email", ensure that you are actually using your email provider's 'outgoing' SMTP settings.
Hopefully, this might help.