4.5.3. Maximum size of message

Important points:

  • Most popular email services, such as Gmail, accept messages no larger than 25 MB.
  • SMTP protocol does not support binary data transmission, so all attached files are encoded using Base64 algorithm, which increases the actual size of the message by 1.5-2 times.

Maximum attachment size when sending via WebMail.Online — 35 MB.

Maximum message size when sent via WebMail classic — 35 MB.

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