External links in outgoing emails

You can place links in emails in the email composer.

For external non-encrypted outgoing emails, we scan the links in your message on our server to prevent spam and abuse. 

If you place a link in an email that leads to a blacklisted or compromised website, we may refuse to send this email.

Again, this only happens with link in external non-encrypted outgoing messages. We have no way of checking links that you place in an encrypted message, as we can't read the message.

We have to scan links in non-encrypted external messages like this to prevent our whole service to be blacklisted because of possible abuse by users.

For checking these links, we use Realtime Blackhole Lists (RBL).