You need to be aware of this.....
Some mail may not be delivered - got this from support after an issue receiving an email: For reference, the email was from a well-known stock-picking newsletter service. It may, in fact, spam people with advertising, but since I'm a subscriber, it's not spam to me. I'm used to other carriers marking email as spam, but still delivering it - this is a non-starter for me (I mean really, incorrect HTTPS formatting?, elements similar to other spam messages?). They really need a way for forwarding these things - I didn't hire a nanny, I hired someone to deliver my email to me.
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The email in question has triggered multiple spam and phishing indicators. To maintain the security of all Proton accounts, our system has rejected emails exhibiting such characteristics.
Although we are unable to disclose specific details, we can provide some general information that may be of assistance.
Common reasons for rejection include:
1. The email contains links whose URL domain and/or IP address may be listed on one or more global blocklists.
2. The email may include one or more URLs with incorrect HTTP or HTTPS formatting.
3. The email body contains multiple elements resembling those found in other spam messages we have identified.
We kindly ask that you report this issue to the sender's IT department. Their technical team should investigate the underlying spam and global blocklist concerns.
Please be advised that emails rejected for these security reasons cannot be bypassed using User Filters or Allow Lists.