Deliverability

There are times when you may be tempted (or legally required) to mail to an old email list. It is a convenient but risky tactic to use when seeking ways to increase revenue. The typical outcome for sending to an old email list is poor inbox placem...

Sending transactional email is a great way to establish and maintain communication with your customers. However, sometimes transactional email is filtered into the spam folder or blocked by a mailbox provider. It is frustrating when this happens s...

When you send steady and predictable email volume, mailbox providers can have more confidence in you. If your volume patterns fluctuate and you sometimes have sudden, dramatic volume increases, you show behaviors mailbox providers often see from s...

The filtering systems used by mailbox providers have methods for classifying email as spam, email that a subscriber may not want to receive. When this occurs and the mailbox provider does not block the email, it places the email in a folder other ...

If your mail is being blocked by a mailbox provider: 1. Review your bounce logs. A policy block bounce contains a Simple Mail Transfer Protocol (SMTP) error code identifying the reason, which can help you determine the cause of the block. The SMT...

When a mail server unsuccessfully attempts to send a message to another server, it typically results in an automated email response called a bounce. Bounces may be caused by a block by the mailbox provider (MBP), and the reason and additional info...

IssueYou see a sharp increase in complaints at one or more mailbox providers.Common causesMany scenarios can cause a sharp increase in complaints:  You stopped using opt-in permission methods with subscribers You recently used a high-risk list ac...

URL shortening, or link shortening, is a technique used to make a URL shorter, but still navigate a user to the desired web page. It is done with a URL shortener program that creates a shorter link to redirect to a webpage with a long URL. Link sh...

One of the most common challenges you may face as a marketer is deciding how to handle inactive and unengaged subscribers on your list. Whether you are regularly sending to inactive subscribers, or you decide to send to a list that has been unused...

It is ideal to keep your subject line length as short as possible, preferably under 55 characters. Many email clients (especially web-based readers) truncate long subject lines. Additionally, some mobile inboxes cut off subject lines at around 30 ...

A dynamic IP address is assigned to a device on a network, such as a personal computer or phone, and may change every time a device connects to the Internet. It is most often used for home and some business users. A dynamic IP address provides fle...

An important decision you have to make as an email marketer is whether to send your email from dedicated or shared IPs. The benefits of these two types are very different. Also, IP reputation works differently depending on whether you are using de...

Determining how many IP addresses your email marketing program needs can be difficult. Whether or not you need one or more IP addresses depends on your email marketing program objectives.Common scenarios A small or mid-sized business that sends a...

Content filtering Content filtering is a technology that scans email, including the header, footer, code, HTML markup, images, text color, timestamp, URLs, subject line, text-to-image ratio, language, attachments, and more. Some content filters ...

An allowlist can have a direct impact on deliverability, especially when resolving temporary failures at certain mailbox providers. An allowlisting indicates to the mailbox provider that you are a more trustworthy sender, but it does not guarantee...

There are a number of things you can do to identify and remove unknown users from your email list. You can: Remove addresses that return a hard bounce. Most unknown user bounces have a 550 error code. Monitor your data and look for hot spots of u...

The Abuse Reporting Format (ARF) is the standard format used by mailbox providers to provide generic spam reports when submitting abuse complaints to other mailbox providers, email service providers, bulk mailers, and subscribers to feedback loop ...

When your email is being throttled by mailbox providers, there are a few steps you can take. In most cases of throttling, mailbox providers send soft bounce error messages back to the sender, indicating that they are limiting the amount of email t...

Although recent statistics show that less than 3% of subscribers view email in text-only format, it is recommended to include a plain-text version of the creative for all messages, especially for emails that rely heavily on images. The plain-text ...

The industry best practice is to aim for a total file size of less than 100 KB, including images and the HTML text.

Senders targeting mobile subscribers should limit total file size (including images and the HTML document) to less than 100 KB. Similar limits may also be appropriate for emails targeted at non-mobile subscribers.

Maintaining a good sending reputation is more important than avoiding spammy words or content in email messages because sender reputation plays a more important role than keywords when it comes to identifying spam.