Why are emails not delivering due to truncated addresses in Sendgrid?
Matthew Whittaker
Co-founder & CTO, Suped
Published 20 Apr 2025
Updated 17 Aug 2025
5 min read
Encountering email delivery issues, especially when addresses appear truncated, can be incredibly frustrating. It's a scenario that often leaves senders scratching their heads, wondering why their carefully crafted emails aren't reaching their intended recipients, even when their database shows the addresses are perfectly fine. This is a common challenge, particularly when using an Email Service Provider (ESP) like SendGrid.
A truncated email address means that part of the recipient's address has been cut off, leading to an invalid destination. For example, instead of client@email.com, the address might appear as client@email.c. This seemingly minor error can have a major impact, preventing delivery and causing legitimate emails to bounce or be dropped.
The core problem usually isn't that SendGrid itself is chopping off addresses, but rather that the truncated address is being passed to SendGrid in the first place. The ESP then attempts to send to a non-existent domain, resulting in delivery failures and perplexing error messages.
Decoding SendGrid's error messages
When emails fail to deliver due to truncated addresses, you'll often see specific error messages from SendGrid that can help diagnose the root cause. One common error is "unable to get mx info: failed to get IPs from PTR record: lookup <nil>: unrecognized address". This message points to a problem with DNS resolution for the recipient domain.
A PTR record (pointer record) resolves an IP address back to a domain name, essentially the reverse of an A record. If the recipient domain is truncated, the system tries to look up an MX (mail exchange) or A record for an invalid domain, leading to the "unrecognized address" error. This means SendGrid cannot find where to deliver the email because the destination domain, as provided, does not exist.
Another common error you might encounter is "error dialing remote address: dial tcp [sender IP]:0->[recipient IP]:25: i/o timeout". This indicates that while SendGrid might have found an MX or A record for the (potentially truncated) domain, it timed out trying to establish a connection or transmit the email. This often happens if the invalid domain resolves to an IP address that simply doesn't host mail or isn't reachable.
Common SendGrid truncation errorsplaintext
unable to get mx info: failed to get IPs from PTR record: lookup <nil>: unrecognized address
error dialing remote address: dial tcp 149.72.160.207:0->34.102.136.180:25: i/o timeout
Understanding the errors
These errors, while technical, ultimately point to an issue with the recipient email address itself, specifically its domain portion. The truncation of the domain prevents proper DNS resolution, which is essential for email routing.
Common culprits and how to investigate
The most likely culprit for truncated addresses is data corruption or an issue in how the email addresses are being passed from your internal systems or database to SendGrid. This isn't usually an issue with SendGrid's platform itself, but rather with the input it receives.
If the truncation is happening before the data even reaches SendGrid, it suggests a problem with your data processing, API calls, or database. For example, a field with a character limit might be silently truncating email addresses if they exceed a certain length, or an encoding issue could be corrupting the string.
Another possibility, though less common, could involve network-related issues between your system and SendGrid's API, leading to incomplete data transmission. However, given that the error specifically points to DNS resolution of the recipient domain, an issue with your data source is generally more probable.
Problem scenarios
Database fields: Email address fields in your database might have a maximum length that is too short, leading to truncation when addresses are stored or retrieved.
API integration: Bugs in your code that prepare or send data to SendGrid's API could be causing strings to be cut off.
Data import issues: If you import contacts, there might be encoding or parsing errors during the import process that corrupt the email addresses.
Investigation steps
Verify source data: Double-check the original email addresses in your database or contact list to ensure they are complete and accurate.
Inspect API payload: Monitor the data being sent to the SendGrid API. Tools or logging in your application can help you see if the addresses are already truncated before SendGrid receives them.
Consult SendGrid support: If your data appears correct on your end, reach out to SendGrid support with the specific message IDs and recipient addresses for their investigation.
Proactive steps for prevention
To prevent email delivery failures due to truncated addresses, adopting robust data validation practices is key. This involves verifying the format and length of email addresses at the point of entry and before sending them to your ESP. Ensuring that your database fields are adequately sized to store full email addresses is also crucial.
Implementing client-side and server-side validation ensures that malformed or incomplete email addresses are caught early. Regular data hygiene practices, such as validating existing email lists and removing invalid entries, can also significantly improve your deliverability. If emails are being clipped in the inbox, or sent to spam, this could be a symptom of broader content or reputation issues, but incorrect addressing prevents delivery altogether.
Remember, a good deliverability strategy also includes proper email authentication (SPF, DKIM, DMARC) and monitoring your sender reputation. While authentication doesn't directly solve address truncation, it builds trust with receiving mail servers and helps ensure your legitimate emails aren't unnecessarily blocked or sent to a blocklist (or blacklist) for other reasons.
Ensure robust email validation
Always validate email addresses both client-side (e.g., in web forms) and server-side before storing them or sending them to your ESP. Use regular expressions or dedicated email validation libraries to ensure addresses conform to the expected format and length.
Regularly clean your email lists to remove invalid, old, or problematic addresses. Services that verify email addresses can help reduce bounces and improve overall deliverability rates, preventing you from sending to non-existent or truncated addresses.
Source of truncation
Preventative measures
Troubleshooting steps
Database field limits
Increase field length to accommodate full email addresses.
Implement robust validation before API calls to SendGrid. Test with long email addresses.
Log API payloads; debug data transformation logic.
Data import/migration
Use proper encoding and parsing during imports. Validate imported data.
Re-import affected data if source is intact, or clean list.
Network/transmission issues
Ensure stable network connection for API calls.
Monitor network logs and SendGrid's status page. Contact SendGrid support.
Views from the trenches
Best practices
Always validate email addresses at input and before sending them to your ESP to catch truncation early.
Regularly audit your database fields to ensure email address columns can store the full length of valid email addresses.
Implement logging of the exact payload sent to SendGrid's API to confirm the addresses are correct at the point of transmission.
Common pitfalls
Relying solely on client-side validation, which can be bypassed, leading to invalid data reaching your database.
Ignoring SendGrid's bounce messages or not analyzing them closely for specific error codes related to truncation or DNS lookup failures.
Assuming your email addresses are correct in the database without verifying the actual data being used by the sending application.
Expert tips
Use email validation libraries in your programming language for robust RFC-compliant checks.
Consider a double opt-in process for new subscribers to verify email addresses are real and correctly entered.
Regularly test your email sending process with various email address formats and lengths to identify potential truncation points.
Expert view
Expert from Email Geeks says a PTR record means the DNS for your sending IP address. A problem in DNS setup for the IP, or for an ISP trying to resolve the IP in DNS, is a common issue. The truncation might have been just in the bounce message and not in the actual send attempt.
2023-08-28 - Email Geeks
Marketer view
Marketer from Email Geeks says their guess is that errors occur because you're sending to invalid domains due to the truncation, indicating a broken TLD (top-level domain).
2023-08-28 - Email Geeks
Final thoughts on email truncation
Email addresses getting truncated in SendGrid, leading to non-delivery, is almost always a data integrity issue on the sender's side. Whether it's a database constraint, an API integration flaw, or a data import error, the key is to pinpoint where the truncation is occurring before the email address reaches SendGrid. By thoroughly validating and cleansing your recipient lists, you can significantly reduce these frustrating delivery failures and ensure your messages reach their intended inboxes.
SendGrid.
