Category : PowerMTA

Email Service Provider versus In-house

A common question among professional senders is: should I use an Email Service Provider (ESP) or can I send my emails in-house? To find a good answer can be difficult. There are a lot of ESPs and a lot of software vendors ready to help you, but where to get objective advise from? My customers [...]

Why I chose a commercial grade MTA

For sending emails, there is a wealth of solutions. On the open source side, there is Sendmail, Qmail, Exim and Postfix. Then there are a number of commercial MTAs available, at different price levels. The most well known vendors are Message Systems, Port25 and StrongMail. Postfix is a popular open source MTA thanks to it’s [...]

Hotmail throttling and PowerMTA

Windows Live Hotmail is famous for throttling senders based on their IP reputation. The following two SMTP errors might be familiar: 421 PR(ct1) The mail server IP connecting to Windows Live Hotmail server has exceeded the connection limit allowed. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help.  For [...]

DKIM recipe for PowerMTA

DomainKeys, and it’s successor DKIM, are important email authentication techniques. Based on cryptography, they are more secure than SPF and Sender ID. With DomainKeys/DKIM the integrity of the content is also protected and authentication does not break when emails are being forwarded. DomainKeys/DKIM is used by large webmail providers such as Google, Yahoo and AOL. [...]