I sent 50 emails. 12 bounced despite SMTP 250 OK.
I sent 50 emails. 12 bounced despite SMTP 250 OK. email, #api, #security, #webdev The 250 OK lie On March 14, my campaign hit a wall. I sent 50 cold outreach emails to hand-collected leads. Every single address had returned 250 OK during SMTP verification. Twelve of them bounced anyway. That's a 24% bounce rate from addresses that were supposed to be "verified." I had trusted the protocol. SMTP…
On March 14, my campaign suffered a setback when I sent out 50 cold outreach emails to verified leads. Despite receiving an SMTP 250 OK response, 12 of those emails bounced, resulting in a 24% bounce rate. I trusted the protocol, believing that SMTP 250 OK indicated the receiving server accepted the email and the mailbox existed. However, I learned the hard way that this is not always the case.
A notable example was test@gmail.com, which passed the SMTP verification with a 250 OK response. While it had valid syntax and an MX record, it was a role address used by Gmail, not an individual mailbox. My SMTP probe gave it a positive response, but a real campaign would have wasted a send, damaged sender reputation, and potentially fallen into a spam trap.
During my investigation, I used the following code to validate the email address:
```python
import requests
url = "https://email-validator112.p.rapidapi.com/email/validate"
querystring = {
"email": "test@gmail.com"
}
headers = {
"X-RapidAPI-Key": "YOUR_RAPIDAPI_KEY",
"X-RapidAPI-Host": "email-validator112.p.rapidapi.com"
}
response = requests.get(url, headers=headers, params=querystring)
print(response.json())
```
The API response revealed that the email was valid in terms of syntax and MX found, but it was marked as a role address with a role type of "test". The deliverability score was 75, not 100, and the address had been involved in several data breaches. These findings highlight the limitations of relying solely on SMTP verification and the need to consider additional factors when assessing email deliverability.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
This story
This is one outlet's version. Read the fullest account.
