1. Reliability of domain name
Domain not listed in Blacklist by Google. Check out: https://mxtoolbox.com/blacklists.aspx. If the domain is listed in BlackList, please replace it.
Note: Gmail is currently updating its Spam filter. Accordingly, the emails containing links will be marked as SPAM and be warned: “Be careful with this message. The email contains a suspicious link that was used to steal personal information. Unless you trust the sender, don’t click links or reply with personal information”. Therefore, you need to check whether the domain name of the link is listed in anti-spam services like: Spamhaus, Spamcop, Barracuda or not. Then try sending an email to your Gmail address to ensure that the link is not blocked.
2. Email address
Using e-mail accounts with user’s name will bring more efficiency, for example: email@example.com. The styles of email like firstname.lastname@example.org or email@example.com, firstname.lastname@example.org are not recommended.
3. The behavior of the mail recipient
Do not send email to recipients that do not want to receive your email. If the recipients mark your email as spam, then your email address will be judged to have low credibility. This will increase the rate of spam mail.
4. Content of email
– Do not insert too many images, large images in email; Do not send email with only one large image or with very little text (because the filter may not “read” the image and list this email in to spam box).
– Do not use capital letters / bold / italics for the entire title and content.
– Do not use too many fonts / font sizes / colors. Text color should not be the same as the email background color.
– Do not insert too many links, do not use short links.
– Do not use too many HTML formats.
– Avoid copying content directly from Microsoft Word/website to email without formatting.
– Do not use too many special characters, exclamation points, dots,… !!!!!!!!!!!!!
– Avoid using attachments. Instead, share your link to your customers.
– Email must have a unsubscribe link so customers can unsubscribe email anytime.
– Personalize content of email and use polite language. Mail filters will know that you are sending email to the right recipients).
– Do not insert keywords that means entice, spam, and scam into the title and content.
– The footer of the email contains brief information about the company, address, contact.
– Do not use of spam phrases such as: Click here, one opportunity in life, free, promotion, discount, make money,…
– The title and the content of the mail should not be the same.
– Check the content with the SPAM check tool integrated in the email editor interface. The minimum point should be about 1.5 and no spam keywords are detected (see section 2.3.
Ways to send email:
– Do not send email to many recipients in the same company (prevent email from being blocked by firewall).
– Try sending test mail to various email addresses (… @ gmail, … @ yahoo, …), then check if the mail comes to spam box.