Why can the error "Mail sender rejection." be thrown ? That the SMTP server responds that such an error occurs?

karastojko / mailio

mailio is a cross platform C++ library for MIME format and SMTP, POP3 and IMAP protocols. It is based on standard C++ 17 and Boost library.

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Why can the error "Mail sender rejection." be thrown ? That the SMTP server responds that such an error occurs? #103

Closed AxeDark13 closed 2 years ago

AxeDark13 commented 2 years ago

Hello,

My question in title, but some details: I used GMail SMTP server(smtp.gmail.com) and STARTTLS-protocol(port 587). The mails I used 100% exists. Credential is valid. I want to find the reason for this behavior by what exactly the SMTP server is responding to.

Thank you In Advance!