Connection to smtp.zeptomail.in:587 has been closed unexpectedly

Connection to smtp.zeptomail.in:587 has been closed unexpectedly

We tested the file attachment email service in the our project. When I uploaded arround 20 MB image, it was successfully sent. However, when attempting to upload a 24 MB image, I encountering the error 'Connection to smtp.zeptomail.in:587 has been closed unexpectedly'.

Previously we have requested for the increase the limit of the attachment size we have received email from support saying now we can send attachment up 30mb but we are encountering error