Bulk email: preparing lists, authentication and unsubscribes

Bear in mind that our email services are intended for business use; for bulk sending for informational or advertising purposes we always recommend using specialised platforms.

Do not assume a campaign is allowed because it is small: check the plan's terms and limits before using its SMTP. On any platform, bad practice can damage the domain's reputation and increase rejections or spam classifications.

Before sending, keep proof of consent, authenticate each source with SPF and DKIM and publish DMARC with alignment. Bulk senders to Gmail and Yahoo must also stay within their complaint thresholds and, for marketing or subscription messages, implement one-click unsubscribe through the List-Unsubscribe and List-Unsubscribe-Post headers in line with RFC 8058, as well as the visible link in the message.

Make unsubscribing easy

Offer a simple way to stop receiving the campaign, also when you send to a regular list.

When someone no longer wants to receive a campaign, they must be able to unsubscribe easily. If the only option they find is marking it as spam, the complaints can harm the reputation of your next sends. Process unsubscribes and do not import those addresses again as active.

Keep the contact list "clean"

Review bounces and exclude recipients with confirmed permanent failures. Tell a non-existent address apart from a temporary problem: repeatedly sending to invalid addresses can harm the sender's reputation.

Some common reasons for rejection:

• Email account that no longer exists or was suspended.
• Email account out of disk space. This may be temporary and does not on its own prove the account is abandoned; delay the retry according to the SMTP code and remove it only in line with your bounce policy.
• Typos in the email address.
• Email account on a domain that no longer exists or has stopped working.

Send gradually and in stages

Avoid sudden peaks and increase volume gradually, especially with a domain or IP that has no history. There is no universal number of recipients that guarantees delivery: Gmail, Yahoo and other providers weigh authentication, reputation, complaints, bounces and past behaviour.

Do not run a campaign by manually splitting lists into messages with dozens of BCC recipients. That technique does not handle consent, bounces, unsubscribes or per-provider limits. Use a tool that sends one transaction per recipient and stops or slows down when deliveries are deferred.

Also bear in mind that there is a limit on emails per hour and per domain, set for security to prevent abuse. This limit can be raised if your daily mail flow requires it, but never for bulk sending.

Staggering helps you control the pace, but it does not turn a campaign into a permitted use of the business SMTP.

Send each email individually

Sending individually means each transaction goes to a single recipient, so addresses are not exposed and unsubscribes and bounces can be handled per person. It is a necessary practice, but on its own it does not prevent a penalty from the receiver.

Doing this by hand is not practical. The next section describes management tools, but it does not authorise connecting them to the hosting SMTP: confirm the permitted use first or use a campaign provider.

Use specialised software

Given the volume, it is not practical to do all of the above by hand. Applications such as phpList, available through Softaculous, manage the pace, individual transactions and unsubscribes. Before connecting them to the hosting SMTP, confirm that the plan allows that use and volume; for campaigns, the recommended option is still a specialised provider.

A desktop application does not turn the business SMTP into a campaign platform or remove its limits. If the tool does not handle consent, one-click unsubscribe, bounces, complaints and reputation, it is not suitable for this use.

Use specialised external services

As we said at the start, it is important to understand that certain volumes require services that specialise in bulk sending.

Our email services are aimed at everyday business use, whereas a campaign needs specialised handling of consent, reputation, pace, bounces, complaints and unsubscribes. Spreading the sending across several IPs does not on its own avoid a bad reputation, and it can make it worse if it tries to get around limits.

Compare platforms on unsubscribe, bounce and complaint handling, domain authentication, delivery logs, data export and cost for your actual volume. Check current limits and features before signing up; a list of brands does not guarantee that all of them will solve your case.

If you use Brevo, see how to authenticate the domain. The hosting can keep hosting the website while the platform handles the campaign.

Before launching the campaign

Test the sender, the links and the unsubscribe with a controlled sample; check SPF, DKIM and DMARC alignment. Review the active recipients and those excluded because of unsubscribes or permanent bounces. Once it starts, watch for deferrals and complaints and stop sending if a repeated failure appears, instead of switching IP to dodge it.