Q: Where can I learn more about Deliverability and Email?
Below are some best practices from the major Email Service Providers (ESPs)

• Gmail Best Practices
• Hotmail (Windows Live) Best Practices
• Yahoo Best Practices
• AOL Best Practices

 

Q: What limits do different providers place on email marketing?
 When selecting an Email Service Provider (ESP), you should be aware that most put restrictions on the amount of email that you can send out.  Below is a summary of different providers and their send limits:

Internet Service Providers

Verizon

• Send limit - no more than 100 recipients per message AND max 500 emails per hour
• Other limits - max 2mb per message
• Email Policy

Comcast

• Send limit - no more than 100 recipients per message AND max 1000 emails per day
• Other limits - max 15mb per message
• Policies

EarthLink

• Send limit - max 1000 emails per day
• Email policy

Cablevision/Optimum

• Send limit - maximum 50 emails at one time
• Other limits - max 20mb per message
• Email policy

Road Runner

• Send limit - max 1,000 emails per day per sending IP address
• Other limits - max 5mb per message
• Email policy

Cox
Specific limits are not published because they vary from time to time depending on a variety of factors, but the limits are set such that a typical user should not be impacted. Cox uses other measures to control spam, including limiting the ability to send email from accounts that Cox believes are being abused, or have been compromised, for the purpose of sending spam.

• Other limits - max 20mb per message
• Email policy

AT&T Yahoo! (formerly SBCGlobal)

• Send limit - no more than 50 recipients per message
• Other limits - max 100mb per message

Charter

• Send limit - maximum 50 recipients / emails per hour
• Other limits - max 10mb per message

BellSouth
BellSouth does not publish a clear email send limit but their policy states "Sending mass, unsolicited e-mail by Service users is prohibited. BellSouth Internet Services reserves the right, in BellSouth’s sole discretion, to determine whether such email constitutes unsolicited messages or transmission." 

• Send limit - BellSouth’s sole discretion
• Other limits - max 10mb per message
• Email policy

WebMail Providers

Rackspace

• Send limit - no more than 250 recipients per message in any given period of time
• Other limits - outgoing messages sent via Rackspace Mail can not exceed 20Mb per email (including attachments)
• Email policy

Google

• Send limit - no more than 500 recipients per message for the web interface, or max 100 recipients when using an email client software such as Outlook, Thunderbird, etc.
• Other limits - max 10Mb per message (including attachments)
• Email policy

Windows Live (a.k.a. Hotmail, MSN)

• Send limit - no more than 100 recipients per message AND max 300 emails per day
• Other limits - max 50Mb per attachment AND max 10Gb per message (including attachments)
• Email policy

Yahoo!

• Send limit - no more than 100 recipients per message AND max 500 emails per day
• Other limits - max 10Mb per message for free Yahoo! Mail, or 20Mb per message for Yahoo! Small Business Mail
• Email policy

Lycos

• Send limit - max 25 recipients per message and max 250 emails per day
• Other limits - max 35Mb per message
• Email policy

AOL

• Send limit - no more than 100 recipients per message or 500 recipients per connection in any given period of time
• Other limits - max 25Mb per message