Limit emails received from the same domain
There are SPAM source verification policies that are based on the amount of emails a given domain is sending per hour.
Such policies can be internal as for example those applied by Google, or general AS IS the example of SPAM lists.
When we talk about optimizing the sending of newsletters from an own solution the first concerns are not to lower the reputation of the sending IP or stay with this same IP present in the most common SPAM lists.
When analyzing this, a question arose:
These days, what limit do companies like Google, Microsoft, Yahoo and others apply to discern whether sending is a trustworthy newsletter or a source of SPAM?
Of course, there are hundreds of methods in use to determine what is SPAM and what is not, but what is intended in this topic is the limit of emails whether per minute, hour or Day, whose even we can not go beyond to ensure that for example Google will not consider a certain address a source of SPAM when it is only sending reliable newsletters!
Then the need arises to know:
┌─────────────────┬─────────────────────┬───────────────┬──────────────┐
│ Controlado em │ Tipo │ Limite por? │ Limite de? │
├─────────────────┼─────────────────────┼───────────────┼──────────────┤
│ Google | Provedor de Email │ Hora │ 100 │
├─────────────────┼─────────────────────┼───────────────┼──────────────┤
| Microsoft | Provedor de Email │ Dia │ 100000 │
├─────────────────┼─────────────────────┼───────────────┼──────────────┤
| Spamhaus │ Lista de SPAM │ Dia │ 1000000000 │
└─────────────────┴─────────────────────┴───────────────┴──────────────┘
Following trying to get these values or a reference line to plan the application efficiently came up with this information:
Google Apps-Receiving limits (English)
...
If an account reaches the limit, a user cannot receive any new email ...┌─────────────┬──────────┐ │ Per minute │ 180 │ ├─────────────┼──────────┤ │ Per hour │ 3600 │ ├─────────────┼──────────┤ │ Per day │ 86,400 │ └─────────────┴──────────┘
But this limit is for app accounts, and for Gmail? What about the others? Is a storm rising in a glass of water?
2 answers
The limits mentioned are for google apps, but probably also apply to gmail.
However, these are limits of receipt and account, which do not interest you, unless you are intending to completely fill the user's inbox with your newsletter, which to me is spam.
What would interest you are sending limits by IP , How many similar emails for different accounts would gmail accept before marking your IP as spammer.
This information is not public and in reality gmail (and no ESP that respects itself) should not use such a technique because all a spammer would have to do to avoid the filter would be to limit the number of spam sent to a certain domain per day.
What you need to do to ensure that your email is not considered spam is to take care of your IP reputation, which is a complicated process... Some tips to put you in the right direction:
Make sure that your IP and other IPs in the neighborhood were not previously used by spammers. To start already with a bad reputation is horrible. Check on listing sites such as spamhaus and sorbs. Use mxtoolbox to see if your IP is not currently listed, and do so periodically. Oh, obviously your IP should be Fixed .
Make sure your newsletters include a 'one click unsubscribe' link. And that users who click on it do not need to log in to remove themselves from your list and will no longer receive your newsletters.
Use a double opt-in process, registration is only confirmed when the user clicks on the link in the confirmation email.
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Make sure that your MTA's hostname has an A record and that the reverse resolution is valid. Hostname -> A - > Hostname
Make sure your MTA cannot be used as an 'open relay'.
Use the MXtoolbox tools to see if there are other things to fix in your DNS.
Ask your users to add it to the address list.
When these things are working properly, investigate:
- DKIM
- SPF
- Feedback Loops
- List-Unsubscribe header
The most important thing is to make sure that those who are receiving your newsletter want to receive it, can remove themselves from the list when they want and that their content is relevant.
I think that starting from the principle that google offers a free email to the end user, as well as hotmail, there is no way to reach the mailboxes of these users, in these services, efficiently, without a financial agreement, starting from a single IP. My tip would be that in case of mail marketing, you set up a large range of MX, and preferably in several domains. Thank you metric palas already obtained and made available!