Supported email messages

SmartRelay supports standard RFC 5322 (MIME) inbound email messages, delivered via ESMTP (RFC 5321).

CC: BCC: and Multiple TO:

Cc: Bcc: and multiple To: are not supported by default. These features can be activated on specific request. The acceptance is left to the discretion of Contactlab.


  • The use of one CC:/BCC: for each message sent will consequently double the total number of recipients reached. This affects the sending volumes and prices.
  • As a consequence of what stated above, statistics will be altered, as all addresses in CC:/BCC: or multiple TO: will be included as recipients of that delivery.
  • Messages received by recipients in CC:/BCC: may not be an exact copy of the message sent to the addredd in TO: as per the presence of dynamically personalized content.
  • Pay attention to the information included in the email body. For example, if the message contains passwords or other critical information, consider the CC:/BCC: adresses will be able to read it.

Apart from a few exceptions, we do not modify headers. See Email headers for more details.

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SMS Message Requirements