Email Delivery and Deliverability FAQs

Delivery refers to whether a mailbox provider accepts a message. Deliverability refers to how a mailbox provider determines where to place a message, such as in the recipient's inbox or SPAM folder.

Our team of email specialists work to resolve most delivery issues. In the event an issue is the result of a sender's behavior, we work with the organization to help them improve their sending practices.

As an email service provider (ESP), we conform to standards for high-volume senders to ensure email delivery. We use our system in combination with a dedicated team of email specialists — who constantly monitor changes that occur within our system and throughout the industry — to help ensure your messages reach their intended recipients.

To prevent mailbox providers from considering your messages as SPAM, we encourage you to follow these deliverability recommendations.

Blackbaud's servers send processed messages to our Mail Transfer Agent (MTA) servers, which physically transmit messages using SMTP protocol to mailbox providers through multiple shared Internet protocol (IP) addresses. After our system transmits a file, the mailbox provider determines whether to accept it.

Specifically, they consider:

  • Blackbaud's sending practices and reputation to determine whether to accept the delivery of a message.

  • The sender's content to determine the deliverability of the message. Deliverability refers to how a mailbox provider determines where to place a message, such as in the recipient's inbox or SPAM folder.

To determine deliverability, mailbox providers consider the:

  • Recipient's previous engagement with the sender's messages, such as whether they opened them or clicked links

  • Email's design and composition

  • Reputation of the sender's domain

Sometimes, when we attempt to transmit a file, the server doesn't accept it and instead returns a soft or hard failure (bounce) code. We organize these codes into failure reason categories and include them with the bounce failure codes in reports to help you understand and correct problems. For more information, see Soft and Hard Failures.

Since Blackbaud doesn't control your organization's domain, email sent from your Blackbaud website is not technically sent from your @domain.org domain, even though you may have entered it in the "send as" or "send from" email address field. Email messages are actually sent from Blackbaud's Mail Transfer Agent (MTA) servers. As a result, your receiving mail server may not recognize the domain.

To help mailbox providers — including the receiving mail server for your organization — verify that you are a legitimate sender, our email system supports multiple authentication methods for your domain. Since you own your domain, we rely on you to manage the authentication for it.

Also, to ensure your anti-SPAM systems don't filter out email you send to yourself from our servers, we recommend you work with the administrator of your network’s email system to whitelist the following ranges of IP addresses.

For Altru, Blackbaud Internet Solutions, Blackbaud NetCommunity, and Online Express:

  • 205.139.104.0/22 (205.139.104.1 - 205.139.107.254)

  • 216.235.196.0/22 (216.235.196.1 - 216.235.199.254)

  • 216.235.200.0/21 (216.235.200.1 - 216.235.207.254)

For Luminate Online:

  • 66.45.103.0/25 (Transactional email)

  • 69.48.252.128/25 (Transactional email)

  • 64.244.120.32/27 (Bulk/campaign email)

  • 64.244.122.192/27 (Bulk/campaign email)

  • 64.244.127.128/27 (Bulk/campaign email)

  • 64.244.127.160/27 (Bulk/campaign email)

  • 216.235.195.0/24 (Bulk/campaign email)

Since Blackbaud doesn't control your organization's domain, email sent from your Blackbaud website is not technically sent from your @domain.org domain, even though you may have entered it in the "send as" or "send from" email address field. Email messages are actually sent from Blackbaud's Mail Transfer Agent (MTA) servers. As a result, your receiving mail server may not recognize the domain.

To help mailbox providers — including the receiving mail server for your organization — verify that you are a legitimate sender, our email system supports multiple authentication methods for your domain. Since you own your domain, we rely on you to manage the authentication for it.

Also, to ensure your anti-SPAM systems don't filter out email you send to yourself from our servers, we recommend you work with the administrator of your network’s email system to whitelist the following ranges of IP addresses.

For Altru, Blackbaud Internet Solutions, Blackbaud NetCommunity, and Online Express:

  • 205.139.104.0/22 (205.139.104.1 - 205.139.107.254)

  • 216.235.196.0/22 (216.235.196.1 - 216.235.199.254)

  • 216.235.200.0/21 (216.235.200.1 - 216.235.207.254)

For Luminate Online:

  • 66.45.103.0/25 (Transactional email)

  • 69.48.252.128/25 (Transactional email)

  • 64.244.120.32/27 (Bulk/campaign email)

  • 64.244.122.192/27 (Bulk/campaign email)

  • 64.244.127.128/27 (Bulk/campaign email)

  • 64.244.127.160/27 (Bulk/campaign email)

  • 216.235.195.0/24 (Bulk/campaign email)

To ensure your anti-SPAM systems do not filter out email you send to yourself from our servers, we recommend you whitelist the following ranges of IP addresses.

For Altru, Blackbaud Internet Solutions, Blackbaud NetCommunity, and Online Express:

  • 205.139.104.0/22 (205.139.104.1 - 205.139.107.254)

  • 216.235.196.0/22 (216.235.196.1 - 216.235.199.254)

  • 216.235.200.0/21 (216.235.200.1 - 216.235.207.254)

For Luminate Online:

  • 66.45.103.0/25 (Transactional email)

  • 69.48.252.128/25 (Transactional email)

  • 64.244.120.32/27 (Bulk/campaign email)

  • 64.244.122.192/27 (Bulk/campaign email)

  • 64.244.127.128/27 (Bulk/campaign email)

  • 64.244.127.160/27 (Bulk/campaign email)

  • 216.235.195.0/24 (Bulk/campaign email)

When mailbox providers place messages they suspect are SPAM into recipient junk or SPAM folders, they provide recipients with the opportunity to move them into their inbox and "unflag" them as junk. When users move messages to their inbox or click links within a message, larger mailbox providers such as Gmail rank those senders more favorably.

Deliverability refers to how a mailbox provider determines where to place a message, such as in the recipient's inbox or SPAM folder. To determine deliverability, mailbox providers consider the:

  • Recipient's previous engagement with the sender's messages, such as whether they opened them or clicked links

  • Email's design and composition

  • Reputation of the sender's domain

To improve the liklihood that your messages reach recipient inboxes, we encourage you to follow these deliverability recommendations.

The IP addresses we use to send bulk email include these ranges.

For Altru, Blackbaud Internet Solutions, Blackbaud NetCommunity, and Online Express:

  • 205.139.104.0/22 (205.139.104.1 - 205.139.107.254)

  • 216.235.196.0/22 (216.235.196.1 - 216.235.199.254)

  • 216.235.200.0/21 (216.235.200.1 - 216.235.207.254)

For Luminate Online:

  • 66.45.103.0/25 (Transactional email)

  • 69.48.252.128/25 (Transactional email)

  • 64.244.120.32/27 (Bulk/campaign email)

  • 64.244.122.192/27 (Bulk/campaign email)

  • 64.244.127.128/27 (Bulk/campaign email)

  • 64.244.127.160/27 (Bulk/campaign email)

  • 216.235.195.0/24 (Bulk/campaign email)

SPAM blacklists are domain and IP address inventories of senders with poor reputations which sometimes help mailbox providers determine whether to place messages in recipient inboxes. Large trustworthy companies, as well as small, independent networks, create these lists and each provider uses them differently. Typically, mailbox providers combine data from various public blacklists — as well as information from their own networks — to determine the credibility of a sender. Subsequently, many lists have little to no effect on IP reputation. Major providers disregard low-priority lists entirely and only use information from high-priority services such as SpamHaus and SpamCop.

Blackbaud subscribes to ReturnPath — the email industry’s leading deliverability solution provider — to monitor external blacklists for our IP addresses. When necessary — such as on the rare occasions when SpamHaus or SpamCop list our IP addresses — our team of email specialists immediately request to delist them. We recommend you use services such as uribl.com to monitor your domain and, if necessary, request to de-list it.

Note: Blacklist companies don’t block messages. Rather, mailbox providers use the listings as reasons for blocks. To prevent blocking, we recommend you manage your list quality and maintain a database of engaged recipients.

Although we use measures to prevent external blacklisting, email senders’ practices ultimately determine the reputation of the shared IP addresses. If one of our IP addresses appears on a reputable blacklist, we take the corrective actions necessary to remove it.

Note: Some disreputable blacklist sites charge fees to remove IP addresses, only to add them back hours later. Mailbox providers don't consider these blacklists valid, and neither does Blackbaud.