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.
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): http://g.live.com/1rewlive4tup/tupp 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.
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