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  • Messages are sent very quickly, thanks to a robust and scalable infrastructure that guarantees immediate sending (except in case of grey listing on destination servers). 
  • There are no bandwidth restrictions and a dedicated channel is used for sending these messages (no queue-related delay). 
  • Automatic processes can be activated following actions that users might have performed.
  • NOTE: this channel cannot be used to send bulk email messages, but rather only for transactional emails. There are limitations in place that prevent system abuse (see API use policy).


titleClick here to expand and learn how you can send transactional messages using MailUp

MailUp can send transactional emails in three ways. Depending on the speed and on the amount of messages to be sent, you can choose between them or, even better, you can mix them to get the best result.

By using the method used to send confirmation messages

MailUp sends a confirmation message to subscribers through an automatic procedure. Subscription can take place in two ways:

The content of the subscription confirmation message can be edited, so to make it correspond to the template of the message you want to send (there is only one confirmation message for each list, but you can set up multiple lists within your MailUp account).

The confirmation message can be personalized with the recipient's personal data by using dynamic fields (up to 40 available when purchasing the Marketing+ package).

These emails can also contain a link triggering an action (opening of a messages page and automatic sending of another email), through the use of SUB link. A specific list can be created for the purpose, and each list can have a different sender address. 

By using Web services

A web service allows the immediate sending of a single message. This procedure is much more flexible, but it is paramount to follow the instructions provided in the section describing this function.

The WS_MailUpSend.SendSingleNewsletter allows to send an email message with the indication of subject, recipients and contents. Dynamic fields (i.e. placeholders that are replaced with recipient's personal data values before sending) are supported, while dynamic content is not supported.

This is the best choice for transactional messages that have to be delivered in few seconds (e.g. password reminder, account credentials after signup), but this solution has some limitations (see API use policy and the box below). In many cases you can have a good trade-off by using either web services and SMTP relay service.

When using SendSingleNewsletter(), the best practice is to use predefined messages with dynamic sections, and not to create a brand new newsletter for each call. In this case MailUp would keep on using space to store the new content, which can negatively affect performance for your MailUp account. If you are in need to send hundreds (or more) of fully personalized transactional messages and you cannot use a predefined message, please contact us
By using SMTP relay service

With SMTP+ feature, your application can take advantage of a high deliverability SMTP server provided by MailUp. No need of integration with MailUp API, all you need is a set of SMTP credentials. SMTP+ offers a scalable solution that is valid also for high volumes of transactional email messages to be sent. There is a couple of things to know: delivery time depends on the bandwidth agreed for that console account and dynamic fields are not supported. This is the best choice for big amounts of personalized messages that do not have to be delivered in few seconds.