Troubleshooting B2B deliverability can be a challenge. Many companies deploy third-party spam filters (e.g. Mimecast) in addition to their email client (e.g. Microsoft Office 365) to protect their users from spam and phishing attacks. The filters are highly customizable, so you could send email to different businesses with the exact same filters in place and get different placement results.
Before you start troubleshooting your B2B deliverability problems, it's a good idea to know your subscriber domain distribution. Many B2B companies send to both B2B and B2C domains and popular B2C domains such as Gmail and Microsoft can be used to help you troubleshoot. Gmail and Microsoft have similar default filter setups for their enterprise customers (Google Workspace and Office 365) so adhering to their published B2C best practices can also help with delivery to corporate domains.
Follow these troubleshooting steps to help determine a cause of your B2B deliverability problems.
1. Determine the scope of the deliverability problems
Check your Inbox Placement results in Everest (In-Flight>Inbox Placement>Inbox Tests) to determine which B2B hosting or filter companies are showing deliverability problems.
Are the problems:
- For one campaign or for all campaigns?
- For a specific IP address or domain or all IP addresses or domains?
- Only for your promotional campaigns or do they only affect transactional or other triggered messages?
- For a specific email stream like a product line or webinar promotions?
- Occurring on a specific day or time of day?
- For just one hosting or filtering company, or do you see similar problems at other hosting or filtering companies?
- For a specific segment of subscribers or all subscribers (e.g. new leads, existing customers)?
- For a specific brand you own or all brands?
- For a specific email template or content?
2. Check performance metrics for trends
Look for large, sudden increases in complaints, unknown users, spam traps and unsubscribe requests along with declining response metrics to help pinpoint potential causes for deliverability problems.
In Everest, check your:
- Reputation and Engagement trends for complaint and engagement data (FBL and ESP integrations required). If you don't have the integrations set up, use your existing internal or ESP reports.
- Certification trends and IP performance. If you participate in Validity’s Certification program, the data can be useful in identifying potential causes of your deliverability problems.
- Sender Score in Everest (Monitoring>Reputation) is a good indicator of overall email health. Look at the trends tile for the past 30 - 90 days for unexpected fluctuations in your score and metrics. The dates can help you focus in potential problem areas (e.g. a recent trade show, campaign, or list acquisition).
3. Are you using a new domain or IP?
- Have you warmed up your new IP or domain?
- While warming IPs and domains are typically reserved for B2C non-corporate mailbox providers such as Gmail or Microsoft, if part of your subscriber list is sent to these and other mailbox providers, a warm up is necessary and recommended.
- Ask your ESP when the last time email was sent from your new IP. Most ESPs recycle IP addresses and you may inherit the sending reputation of the previous sender if the IP was used within the last 6 months.
4. Determine if your IP addresses or domains are on Blocklists
If your IP address or domain is listed on a blocklist, refer to the Blocklist’s listing criteria and fix the cause. Everest alerts you to blocklist issues (Monitoring>Reputation) if you have created monitoring profiles for your IPs and domains, but you can also check your SMTP logs for error codes and descriptions indicating a blocklisting.
Not all Blocklists are created equally as many of them are minor and have little to no effect to your deliverability. Important B2B blocklists such as Proofpoint, Barracuda, Spamhaus, URIBL and SURBL can have a negative impact to your inbox placement if your IP or domain is listed. Typical reasons for being blocklisted are because of a high number of complaints and sending to spam traps.
- Proofpoint (IP)
- Barracuda Reputation Block List (BRBL) (IP block list)
- MX Toolbox (IP)
- Spamhaus DBL (domain)
- URIBL (domain)
5. Check your SMTP logs for clues regarding the issue
If your email is being throttled or blocked, check your SMTP logs for a response code indicating a possible cause. Many mailbox providers provide a response code, a short description and a link to their postmaster page you can use to troubleshoot. If you use an Email Service Provider (ESP), ask them if they have a report you can run that lists these response codes.
Everest Inbox Tests can also indicate throttling issues by looking at Minutes to Receive (MTR). If seed data takes longer than two minutes to populate, it may indicate throttling or a network issue.
6. Check your sending reputation
In addition to checking your Sender Score metrics, also check your sending reputation with the following filter providers for additional troubleshooting help.
- Cisco IP & Domain Reputation Overview
- Barracuda Central
- Cyren IP Reputation Check
- Trend Micro Email Reputation Services
- Symantec IP Reputation Investigation
- Proofpoint Dynamic Reputation IP Lookup
- Google postmaster
- Reputation data is for all Gmail and Google Workspace accounts.
- Account sign up and activation required to see reputation results.
7. Check your technical configuration
- Ensure your IP is configured with a valid reverse DNS record. Your IP address needs a valid, non-generic reverse DNS (PTR) record pointing to a domain. A missing or generic (in-addr.arpa) reverse DNS record can cause deliverability issues.
- Ensure all domains have a valid A (IPv4) or AAAA (IPv6) record.
- Ensure your domain has a valid MX record and your email server is accepting incoming email.
- Determine if your email authentication is working properly. A misconfigured SPF, DKIM or DMARC record can result in email being filtered or blocked. Check for the “Authentication-results” in your email headers using Everest Inbox Placement to determine if there are any verification failures. A DMARC record with a p=quarantine or p=reject policy flag can cause spam folder placement or rejected messages from your domain if SPF and DKIM are failing verification.
- Ensure you are signed up with all available complaint feedback loops and that the process to suppress complainers is working properly.
- Check if any of your website domains have redirects. Too many redirects may be perceived by a spam filter as an attempt to hide the destination.
- Ensure your sending system is secure and has not been accessed by an unauthorized third party to send spam.
- Check your retry settings. Increase the time between retries if experiencing throttling issues. You may want to limit the number of retries per message to 2 or 3 temporarily if needed until you can isolate a cause of the deliverability problems.
- Check your connection and throughput settings. Mailbox providers will throttle your email if you are sending too much email to their servers. Reduce the connection and throughput settings if throttling occurs.
- Ensure the bounce processing process is working and unknown users are suppressed or removed after one bounce.
- Determine if your bulk marketing email and corporate email share an IP address or domain. Ideally, marketing related messages should be sent from a separate IP address and subdomain than used for standard 1:1 corporate communications. If they do share the same IP and domain, it may cause deliverability problems.
8. Check your content
- Send your content through Everest's Design & Content feature (Pre-send>Design & Content) and make sure it is rendering properly across all of the email clients. Improperly rendered campaigns may lead to lower response rates and higher complaints.
- Use Everest's Design & Content feature to ensure all links work as expected and go to the correct landing page.
- Check your friendly-from address. Does your friendly from reflect the relationship with the recipient? Email sent directly from a sales person to a new lead with no brand recognition may cause some recipients to perceive the email as spam.
- Ensure information such as your business address, phone numbers, and website address are accurate. Some B2B filters look at this information to help determine if it is associated with your brand.
- Ensure your website or image hosting site does not have malware.
- Check your content for link shorteners. Link shorteners are often used by spammers to hide the destination domain.
- If you send attachments, ensure they are virus free.
- Ensure you aren't showing or asking for any personal identifiable information (PII) such as credit card numbers or social security numbers. In some cases, this information may be accidentally inserted into your email because of a coding or database mistake.
- Ensure your content is relevant to the subject line. A misleading subject line may be perceived as spam and cause a recipient to mark a message as spam.
- Check for unexpected HTML code in your email template. If you copied HTML code from Microsoft Word or Publisher, you may have extra HTML code that is triggering a warning flag with a spam filter.
9. Review your list acquisition and list hygiene processes.
- Find out if you recently acquired email addresses from a higher risk source such as a list purchase, e-append, or list scraping and stop sending to those email addresses until you can verify they are valid addresses with Everest's List Validation or BriteVerify.
- Using these methods to acquire email addresses are not recommended because they can harm your sending reputation.
- If you have a co-registration partner, you may want to temporarily stop sending to addresses acquired from them until you can verify that the email addresses opted in to your email program.
- Look for unexpected large spikes in the number of new subscribers over the past 90 days. If you average 100 new subscribers a day and you see that number suddenly spike up to 1000 over a few days, it may indicate list poisoning. Suppress those email addresses until you can verify they are real subscribers with Everest's List Validation or BriteVerify.
- It's always possible an increase is due to a recent event or promotion, but you should know if that is the case.
- Ensure your list hygiene plan is working as expected. Sending to a large number of subscribers that don't engage with your email can cause deliverability problems.
Additional troubleshooting tips
- Determine if you increased the frequency of email sent to subscribers. If you started sending more frequently for the latest holiday or special event, it could be leading to more complaints, unsubscribes, lower engagement rates and more messages that are deleted without being read.
- You may need to send less frequently in order to bring sending metrics back to optimal levels.
- Determine if your content contains a spammy Cloudmark fingerprint. Cloudmark is owned by Proofpoint, a popular B2B spam filter and many filtering companies use Proofpoint and Cloudmark in their filtering decisions. After identifying and fixing the cause for the spammy fingerprint, submit a reset request. If you don’t fix the cause of the issue, your content is likely to be marked with a spammy fingerprint in the future.
- Determine if you sent a large volume of email in a short period of time. Large volume spikes may be perceived as spam. If it was a one-time event, monitor performance over the next few days to see if deliverability normalizes. Spread out future large volume sends over time to avoid being perceived as a spammer.
- Determine if you sent to a suppression list. If you did send to a suppression list, your performance should normalize as your metrics return to normal levels. Many senders send to a suppression list by accident, but some senders send to a suppression list to try and re-engage old subscribers, which usually results in deliverability problems.