PHPMailer sends an SMTP extension command with the sent emails as below which can be used to get the usage report of PHPMailer on the ESPs(Email Service Providers):
BBC World Service | National Park Service | Internal Revenue Service | Distinguished Service Order | Special Air Service | United Parcel Service | Meritorious Service Medal (United States) | United States Postal Service | National Health Service | Meritorious Service Medal | Metropolitan Police Service | United States Forest Service | German Academic Exchange Service | Secret Intelligence Service | Immigration and Naturalization Service | Distinguished Service Cross | National Defense Service Medal | National Service | United States Secret Service | Royal Naval Air Service | National Weather Service | Agricultural Research Service | Special Broadcasting Service | Distinguished Service Cross (United States) | On Her Majesty's Secret Service (film) | On Her Majesty's Secret Service | Internet service provider | email | United States Foreign Service | Distinguished Service Medal |
In the spring of 2006, the company publicly launched Pando, a small application that let consumers bypass email's attachment limits and send large files (up to 1GB) regardless of email service provider.