Outlook is blocking my mail bot

Question

I've set up a basic website where people can also create an account.

This feature is protected against spammers by using a reCAPTCHA and an email verification system, to send a verification link to the users, so that I can verify the authenticity of the email address they've provided in the login form, which doesn't work.

Everything is fine for the first 2 mails, but then the webserver throws an Exception which basically says that the connetion to Outlook servers has been closed. In my bot's inbox there's an email (sent by Outlook itself):

Hello name, To continue sending messages, please sign in and validate your Outlook.com account.
This helps us stop automated programs from sending junk email.
Thanks for your help and patience!
The Outlook.com Team

where "sign in" is basically the link to the outlook login page (not spam, it's the true outlook page). After I've clicked on it, the mail system starts working again and it's fine for other 2-3 users, then it gets blocked again and the user doesn't receive any email.

The question is, is there any way to disable this protection and keep sending emails? If not, how can I change my email text to prevent my mail being detected as spam?

I hope there's a solution, because the dedicated machine barely runs the current softwares and honestly I don't want to fix problems on 3 different servers at the same time for such a small project.

• Yes, My bot is sending emails through an Outlook account. I don't have my own SMTP server. The bot only sends emails and the receivers are only the new users, after they've completed the first registration step.
• The emails contain small text, with a link to the website's verification page, for example https://myhostname.com/verify?e=email@email.com&d=41my67verification2random5id41421
• The email doesn't contain any link to ads/spam/... and doesn't even contain such a word.
• The email content is: Per confermare la registrazione sul nostro sito, vai al seguente link: https://... which means To confirm your registration on our website, go to the following link: https://...
• The IP is actually blacklisted only on spamsources.fabel.dk, but I don't think outlook really cares, since validating the email account unblocks the server.
• The exception is of type OutboundSpamException and SocketException: Connection closed by remote host.
• It's not caused by idle time.

Answer 1

Firstly using port 587 isn't enough on its own. This particular error message is common when trying to send email through an SMTP server that you haven't authenticated with. Trying to authenticate with the web link is useless as you need to authenticate the SMTP session. In your SMTP settings you need to specify the server, username (which is your full outlook.com email address), your outlook.com password, and specify TLS/SSL required as yes. Once you have done this your session is authenticated with outlook.com.

Now as you don't mention if you are using a free outlook.com email address or a business paid outlook.com email address I will just add a caveat I have encountered in the past where outlook.com has chucked a fuss at sending what its filters deem to be automated emails when the account is a free account. Couldn't find any documentation on it or even any specific support from Microsoft but it seems like there may be a restriction on free email addresses on outlook.com sending automated emails which should be sent either from a paid account or another SMTP server.