The problem of spam marking by the recipient is manifested mainly in emails sent by scripts or by computer procedures both for single and newsletter mailings.
Send your emails from script or form
This type of email is the most at risk of being marked as spam, as it is close to google's criteria to consider it unsolicited correspondence (spam). The fact that google can spam an email never depends on the server itself, but may depend on several reasons including:
- the script it sends
- the sending mail server configuration
- the IP with which the customer connects to the server
- the content of the email
- the headers created by the script that prepares the mail
- the DNS records of the domain for which correspondence is sent
- Last but not least, by google criteria that are not public and are not entirely known and that are not mentioned in the official google documentation.
To maximize the probability that your newsletter or mechanized email arrives correctly and is not marked as spam, you must pay attention to the following, a series of guidelines created by system technicians through the documentation provided by Google and other public services:
Auth and identify yourself
To make sure Gmail can identify you, follow these steps:
- Use a consistent IP address to send bulk mails; or tries to always keep the same IP
- Keep inverse DNS records valid for IP addresses from which you send email messages, pointing to your domain. Ask your hosting provider what it means if it is not clear.
- Use the same address in the "From:" header in any collective mail you send.
- We also recommend the following, possibly asking the hosting provider to make these configurations, which are quite complex:
- Sign messages with DKIM. Google does not authenticate messages signed with keys less than 1024 bits.
- Publish an SPF record.
- Publish a DMARC policy.
- Learn more about email authentication.
- Additional guidelines for IPv6
- The sender's IP address must have a PTR record (that is, a reverse DNS of the sending IP) and must match the IP obtained by DNS resolution to forward the host name specified in the PTR record. Otherwise, the email is marked as spam or may be rejected.
- The sending domain must pass the SPF check or the DKIM check. Otherwise, the email could be marked as spam.
Proper policy formation of the newsletter
If the one you are sending is a newsletter (ie an email addressed to multiple recipients), then you should follow the following lines:
- A user must be able to unsubscribe from your mailing list by one of the following methods: A clearly visible link in the body of a message that directs the user to a page where he can confirm the cancellation of his registration (the user must not be asked for any input, except for confirmation). By replying to your email message, with a request to unsubscribe.
Since Gmail can help users to automatically unsubscribe from your messages, we recommend the following: Provide a "List-Unsubscribe" header that points to an email address or URL by which the user can easily unsubscribe from future messages. Note. This is not a substitute method for canceling the subscription.
- To further ensure that your messages are not marked as spam, we also recommend the following: Automatically cancels the subscription of those addresses that periodically reject multiple messages to the sender. Send confirmation messages to users from time to time. Include each mailing list they signed up for and offer the possibility to unsubscribe to those they are no longer interested in.
- It is possible that your users forward mail from other accounts, so we recommend the following: Indicate explicitly the email address that has subscribed to your mailing list. Support a method of canceling the registration via URL from your mailing list (it is advantageous if the manager of your mailing list is not able to indicate who cancels his / her own registration based on the address "Reply to:").
All messages must be formatted according to RFC5322 (https://tools.ietf.org/html/rfc5322) and, if you use HTML, the HTML standards (http://www.whatwg.org/specs/web -apps / current-work / multipage /).
Messages must have a valid "Message-ID:" header field (https://tools.ietf.org/html/rfc5322#section-3.6.4)
In the messages you must indicate that they are collective messages using the "Precedence: bulk" header field.
Attempts to hide the real sender of the message or the actual landing page of any web links in the message may result in failure to deliver.
The subject of each message must be relevant to the content of the message body and must not be misleading.
Gmail is committed to delivering all legitimate mail to a user's inbox, however some legitimate messages may be marked as spam. Gmail does not accept "whitelisting" requests from bulk message senders and we cannot guarantee that all your messages will bypass our spam filters. To ensure that our users receive all the messages they want, we have provided them with a method to send us comments on messages marked as spam: users can select a "Not spam" button for each message marked by our spam filters. We listen to user reports and correct problems to provide them with the best product experience. As long as our users do not consider your mail as spam, you should have no delivery problems from your inbox.
Two important factors, under normal circumstances, help messages reach the Gmail users' inbox:
The address in the "From:" field is present in the user's contact list.
A user clicks "Not spam" to alert Gmail that messages sent from that address are required.
If you send both promotional mail and transactional messages related to your organization, we recommend that you separate the mail as much as possible based on the purpose. You can do it this way:
Use separate email addresses for each function.
Send mail from domains and / or different IP addresses for each function.
By using these tips, important transactional messages are more likely to be delivered to a user's inbox. Our guidelines help you build a good reputation within the Gmail system, resulting in continuous delivery of your messages to Gmail inboxes.
If, even following all the precautions indicated above, the sending of emails (even if passing the indicated checks) still produces emails that are marked as spam by gmail, then a further solution may be the connection to the google smtp to send the correspondence. However it should be kept in mind that this SMTP imposes restrictions on the number of outgoing emails.