How to avoid email autoresponders getting into the spam service?

Question

gmail

Now we are developing a new resource - something like a VIP email autoresponder for public people - musicians, writers, scientists, etc. The essence is simple - the client on our site enters his email, smtp and pop3 server settings, login and password. Our system regularly receives letters by itself, processes them according to very tricky algorithms and sends answers. By creating the illusion that a real person is responsible, not a program. So to say, the results of Turing tests - to life!
However, a problem has arisen - a significant part of our clients have mailboxes on free domains - mail.ru, yandex.ru, gmail.com, etc. ), as we will immediately be blocked by spam filters, since too many letters will be sent from one IP address. We consider - well, let's say on average from one client 20 letters per day, multiply by 1000, we get 20,000 letters per day. Divide by 3 (equal on average for free email domains) - about 7,000 emails per day from one IP to a free resource. Whereas from one IP, for example, mail.ru allows you to send no more than 250 letters per day. How to solve the problem?

The peculiarity of the situation is that no more than 200 letters per day with unique content will be sent from each individual account to real addresses. However, all pop3 and smtp communication sessions will occur from the same IP - from our server. It will be similar to the situation when there are about 1000 users behind one IP who regularly work with their mailboxes on mail.ru, yandex.ru, gmail.com, etc. using the pop3 and smtp protocols.

Solutions were considered:

• Contact the support services of major free mail services to add our IP to the exclusion list. However, it stops the negative experience of communicating with such services, incl. this experience was also discussed on Habré.
• Somehow hide your real IP when sending. The question is how? If you use, for example, a paid VPN or socks, then the mail resource will still see a different static IP, not ours. And still block us. Or am I wrong? Or are there other ways to hide your IP?
• Connect to the Internet with a dynamic IP and reconnect every hour. However, where is the guarantee that when reconnecting we will be allocated a new IP, and there will be no IP left from the previous session?
• Force customers to start paid email from providers. However, our service is for poor people. And extra spending can scare away potential customers. In addition, the client may already have a mailing address known to his colleagues on a free resource, and he will not want to change it.
• Place a module that directly sends letters on the client's computer. Then the IP will be different, as well as email accounts. However, the client computer may be turned off for a long time. For example, when a client is on a business trip or on vacation. And the very essence of an email autoresponder is that it should always work, regardless of whether the client's computer is turned on or not.

Now this problem is the main one for the whole project. Please tell me how to deal with it? Particularly interested in real experience in such situations.

Answer 1

There are also a bunch of saas'ov who are engaged in sending mail, so send it through anyone. The boxes just have to be confirmed.

Connect to the Internet with a dynamic IP and reconnect every hour. However, where is the guarantee that when reconnecting we will be allocated a new IP, and there will be no IP left from the previous session?

In what data centers is this possible? Just don't say that all this will be spinning on your home computer.
PS: It will not take off, I can hardly imagine a person who will give you access to all his mail, and even allow you to send it on his own behalf.

Answer 2

And why did you decide that the limit on mail.ru is 250 letters per day?
We have a service for sending E-mail notifications about concerts.
We were also worried about getting into spam, we did SPF, DKIM, PTR - there are no problems.
Every day, several thousand letters go to mail.ru.
It seems to me that you should rather be afraid that some other answering machine will not answer your letter (for example, that a person is on vacation).