When we receive a returned email after sending it, in most cases we can detect the reason for the return.

In this tutorial we will focus on the return "550 high probability of spam".

Our Relay service makes this return when the email being sent has a high probability of being considered spam.

Here are some negative factors that can affect the email being considered spam:

- there is no mailbox for the sender: by default the relay PREVENTS its sending.
- small content: emails without text or a short phrase.
- certain keywords: offer, trial, test, viagra...
- meaningless letter groupings like "dfwefqf" in subject or message
- attached files: the email system is not the ideal way to send large files. For this we recommend an external service such as wetransfer
- external links: especially repeated ones. And if the website it points to is listed, the sending will be blocked directly.
- incorrect email encoding. (custom scripts must be properly encoded)

Here are some recommendations:

We would also like to recommend that this service is subject to the terms of use indicated on our website, and is not suitable for mass newsletter, notification or commercial mailing. If you require this type of shipment, please use a commercial service adapted for this purpose.