Am I allowed to contact a user who contacted me through the PM form to promote services or products that I don’t sell on Envato marketplaces?
Author terms state:
(you cannot) attempt to contact other members through the Envato Market or use any information gained from the Envato Market with the intention to make a private arrangement that would otherwise be made using the Envato Market;
When a user sends me an email I gain his email from Gmail, not from Envato, what do you think about it?
You gain his email from Envato. It may come through Gmail, but it is Envato who fa ciliate and instigated the sending of the email.
However, they key line in your example is “that would otherwise be made using the Envato Market.” In that, if it’s relating to products or services that aren’t available on Envato, then it’s not really possible for you to make an arrangement through Envato… so you’re OK.
So if you want to sell your cat, then there’s no Envato marketplace for selling cats, so you’re welcome to sell your cat to the user via email. The purpose of that section in the author terms is mainly to clarify that you’re not allowed to make deals, or offers, or different licensing terms, or packages of products or services that are already available on Envato.
Although, obviously make sure you don’t go spamming users with products or services that they don’t need… they might not like that.
Try sending an automated message when you get contacted. Something like:
Thank you for reaching out. We shall contact you shortly. In the meantime we have also added you to our mailing list and will email you from time to time with notifications about new products or updates to existing items to serve you better.