How to pass Gmail spam filter?

According to statistics and the web trend, Gmail has no doubt become the most widely used email service in the world. When sending mass emails, a large portion of emails go to Gmail.

Therefore, it is important for every email marketer to know the basic spam filtering rules of Gmail and how to avoid them. By following some best practices can significantly increase your email deliverability.

Gmail Market Share
Gmail Market Share

Here are four types of emails that Gmail would very likely consider as spams:

1. Phishing scams

Some spammers try to get your bank account password or credit card information through emails.

What you should do: Email marketers usually won't fall into this trap, as long as you are sending legitimate marketing or sales related emails.

2. Unknown sender

Some spammers can fake messages as if they were from a trustful website or company. But these messages do not have correct authentication information. Gmail may put these mails into junk mail box.

What you should do: If you send mass emails through a third-party email marketing software, make sure you set up SPF record or DKIM correctly.

3. Messages previously considered as spams

If your recipients consider your emails as spam for several times, very likely, all your future emails will fall into their spam folders forever. It may also affect your domain reputation.

What you should do: Always provide an easy channel for your recipients to unsubscribe from your list if they do not like your emails. An alternative method is to get your recipients to add you into their contact list. This way, even if you made a mistake in using too many spam sensitive keywords or invalid authentication info, your emails would still arrive safely in your recipients' inbox.

4. Similar to other spams

Gmail learns from user behaviors about the characteristics of spams. So Gmail is always updating its own algorithm in detecting spams.

What you should do: Subscribe various email newsletters from well-known companies. Learn from those emails that you see in your inbox. Those companies are always updating themselves and follow the email marketing best practices. They will teach you what a healthy and professional email should look like.

Feel free to read the original post from Google and share your thoughts below:

How to select a healthy SMTP server for your email marketing campaign?

If implemented correctly, email blasting is the most powerful and has the highest ROI among all marketing channels. The first thing to do before you send out your email campaign is to select a healthy SMTP server to deliver emails. If you made a wrong move at this step, you would be risking your capital and the reputation of your company.

There are usually three types of email SMTP servers you can choose:

1. Partner Email SMTP Servers

These email service providers (e.g. Gmail, Yahoo! Mail, Hotmail, AOL Mail, etc.) sign agreements that emails from each other's server will never be blocked and there is no limitation on the number of emails sent per day. The only limitation imposed is on the content of the email. Therefore, as long as you avoid using those spam keywords in your email, and do not send mass emails too fast, most of your emails will be delivered safely and accurately. By utilizing professional email marketing software, like 1and1Mail, you can get your job done very easily.

1and1Mail SMTP Server Setting

2. Email SMTP servers with healthy records

To ensure a SMTP server has a healthy record, there are three things to check. (1) The servers have fixed IPs and they are not in the blacklist of international anti-spam association. (2) The Reverse PTR Records are set correctly. (3) The settings on the SMTP servers are correct. Again, as long as you write good contents and control the speed of sending well with 1and1Mail, your IPs will not be blocked.

3. Unknown Email SMTP servers

These servers usually use dynamic IPs, do not have a correct DNS records or reverse PTR records, or are blacklisted by many well-known email service providers. Emails sent from these servers would be easily blocked or go into junk mail box.

To conclude, do some research on the email SMTP servers you are using. Moreover, do not be too aggressive when sending mass emails. Use them properly with professional email blasters to build up reputation of your domain and email account.

Why my IP is blocked by email service provider when sending mass emails?

Some email marketers may encounter IP banning when sending mass emails through 1and1Mail. Whether or not your IP will be blocked depends on the following things:

1. If you are using your company email accounts or paid email accounts to send mass mails, your email service provider will simply suspend your email account or SMTP connection. Your IP is safe in this case.

2. If you are using free email accounts from Gmail, Yahoo! Mail, or Hotmail, and using dynamic IP through dail-up. Your IP will be temporarily suspended, but it will be resumed soon, because the IP will be assigned to someone else next time.

3. If you are doing mass mailing through a static IP, it is very likely your IP will be suspended until you contact your ISP and explain the reason.

In 1and1Mail 3.2 (to be released at the end of Oct), the Auto IP Switcher feature can help avoid the above situations as much as possible and increase your email deliverability.

POP and SMTP Server Settings of Gmail, Hotmail, Yahoo! Mail and More

If you handle mass mailing through desktop email clients, you have to set up the incoming mail server (POP) and outgoing mail server (SMTP) correctly before you start sending and receiving emails.

Here 1and1Soft summarize POP and SMTP server settings of all commonly used email services. They are all collected from the official sources (namely, the official websites of Gmail, Hotmail, Yahoo! Mail and AOL Mail, etc.). But your email service provider may change its mail server settings without any prior notification. It is suggested you contact your email service provider in case you encounter any error during the account setup or email delivery process.

In most mass mailing software, you only need to set up the outgoing mail server (SMTP server) address and port number because the software is sending mass emails out only.

In 1and1Mail, you only need to set the SMTP server correctly.

SMTP Servers


Gmail POP and SMTP Server Settings

Gmail Outgoing Mail (SMTP) Server:
Use Authentication: Yes
Port for SSL: 465

Gmail Incoming Mail (POP3) Server:
Use SSL: Yes
Port: 995
Note: Enabling POP in Gmail

Account Name: Your full email address (including or
Email Address: Your email address
Password: Your Gmail password

Further reading: Mail Clients Configuration for Gmail

Outlook / Hotmail POP and SMTP Server Settings

Outlook/Hotmail Outgoing Mail (SMTP) Server:
SMTP server needs authentication: Yes
This server requires SSL: No
: 587

Account Name: Your full email address
Email Address: Your email address
Password: Your password

Yahoo! Mail POP and SMTP Server Settings

Yahoo! Mail Outgoing Mail (SMTP) Server:
Use Authentication: Yes
Port: 25 or 587
Note 1: If your Internet Service Provider (ISP) blocks Port 25, you will have to use an alternate SMTP Port number such as 587.
Note 2: AT&T customers use and Port 465 with SSL
Note 3: If you are using Yahoo! Small Business Email, please refer to here.

Yahoo! Mail Incoming Mail (POP3) Server: Only available in Yahoo! Mail Plus

Account Name: Your full email address or your Yahoo! ID
Email Address: Your email address
Password: Your Yahoo! ID password

Further reading: Yahoo! Mail Settings

AOL Mail POP and SMTP Server Settings

AOL Outgoing Mail (SMTP) Server:
Use Authentication: Yes
Port: 587

AOL Incoming Mail (POP3) Server:
Use SSL: Yes / No
Port: 110 for standard or 995 for SSL connection

Account Name: Your full email address
Email Address: Your email address
Password: Your AOL Mail password

Further reading: Send and Receive Emails from Classic AOL Mail Account

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Email Sending Limit and Send Rate – Gmail, Hotmail, Yahoo! Mail, AOL

Free email service providers, such as Gmail, Hotmail, Yahoo! Mail and AOL Mail, usually provide free SMTP connections to send emails and they are the most commonly used channels for mass mailing.

When using the free service, you should pay special attention to the send limits and rate limits imposed by these free email providers. Through using well-recognized mass mailing software and configuring it properly, you can easily go over the limits and save significant marketing cost.

The following data is mostly collected from the official sources (namely, the official websites of Gmail, Hotmail, Yahoo! Mail and AOL Mail). But your email service provider may change its mailing policy without any prior notification. It is suggested you always contact your email service provider and ask about the most updated SMTP email send limits and send rate before proceeding with your email marketing campaigns.

Send unlimited emails


Gmail Sending Limit and Send Rate

Gmail Send Limits: 100 people / connection
Gmail Send Rate: 100 people / day
Gmail Attachment Size Limit: 25MB
Gmail Restriction Expiry Method: Recovered within 24 hours after the limit is reached

Gmail will temporarily disable your account if you send emails to more than 500 recipients or if you send a large number of undeliverable messages.

If you use a POP or IMAP client (e.g. Microsoft Outlook, Mozilla Thunderbird or Apple Mail), you may only send a message to 100 people at a time. Your account should be re-enabled within 24 hours.

Please do verify your contacts' email addresses. It's also important that everyone you are sending mail to is willing to receive it.

Further reading: Gmail Bulk Senders Guidelines

Hotmail Sending Limit and Send Rate

Hotmail Send Limits: 100 messages / connection
Hotmail Send Rate: 100 people / day
Hotmail Attachment Size Limit: 25MB
Hotmail Restriction Expiry Method: N/A

The Hotmail limit for outgoing email messages is 100 messages per day. However, it is not a fixed number!

The limit also depends on your reputation within Hotmail. The system needs a few days to build your reputation. So, there are stricter limitations on new accounts or accounts that have engaged in activity representative of abusers sending spam. As you develop a reputation for not sending junk e-mail, Hotmail increases the number of recipients that you can send messages to.

If you are a new free user, you might be limited to a lower limit compared to an older account which is a temporary restriction and is upgraded to the maximum recipients limit as soon as the user establishes credibility in the system.

You can verify your account with a mobile number (only available in limited markets at this time): to increase the limit immediately. Please note that the SMS validation will increase the limit only if you are hitting a lower limit compared to a regular free user. If you already have the maximum limit of a free account, SMS validation will not help in increasing the limit.

Or, you can upgrade to Hotmail Plus or MSN Premium, both of which are paid accounts, to enjoy a higher sending limit.

Further reading: Hotmail Daily Message Limit

Yahoo! Mail Sending Limit and Send Rate

Yahoo! Mail Send Limits: 20 people / connection
Yahoo! Mail Send Rate: 100 people / day
Yahoo! Mail Attachment Size Limit: 25MB
Yahoo! Mail Restriction Expiry Method: N/A

Yahoo! Mail accepts a maximum of 20 messages per SMTP connection. It is suggested you cap the number of messages you send to Yahoo! Mail to fall within this per-connection limit. When this limit is reached, no further messages will be accepted for delivery as Yahoo! Mail server automatically terminates the connection (without giving an error code).

If you are sending messages to a significant number of Yahoo! Mail users, you may try to reconnect to Yahoo! Mail MX servers immediately thereafter.

You may open concurrent connections from the same server to facilitate efficient transmission of your messages under the help of email marketing software.

Yahoo! Mail also keeps reputation data about each IP address and domain you send from. Therefore, by segmenting the mail stream that delivers marketing mail from another that sends transactional messages, you make it easier for Yahoo! Mail to determine and assign each mail stream's reputation.

If you use Yahoo! Mail Plus, the outbound email messages are limited to 500 per day, and each message can be sent to no more than 100 contacts at once.

Further reading: Yahoo! Mail Basics

AOL Mail Sending Limit and Send Rate

AOL Mail Send Limits: 200 / connection
AOL Mail Send Rate: Constantly changing
AOL Mail Attachment Size Limit: 25MB
AOL Mail Restriction Expiry Method: N/A

AOL also imposes a rate limit on an AOL member when a member exceeds the acceptable number of email messages sent in a given time period. Rate Limits have been put in place by AOL Mail to curtail abuse from spammers and ensure an enjoyable online experience. The maximum number of people you can send an email to is constantly changing so that spammers cannot find out what it is. If you need to send an email to a large group of people, please break your mailing list into the smallest groups possible.

Further reading: AOL Mail Rate Limit

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