Why do I receive a ‘too many syntax or protocol errors’ response when sending emails?
The ‘too many syntax or protocol errors’ response occurs within Outlook if you attempt to send an email to an improperly formatted address.
The error is as follows
Task ‘Mailer – Sending’ reported error (0x800CCC0F) : ‘The connection to the server has been lost. If this problem continues, contact your server administrator or ISP. The server responded: 501 Too many syntax or protocol errors’
How can I fix it?
When you are sending emails using Outlook, ensure that the recipient address doesn’t contain any special characters, such as quotation marks around the address. The server won’t know how to handle this and will generate the error.
This error often occurs when you copy & paste an address into the ‘To’ field without removing the quotations (e.g., ‘name@website.com’ instead of just name@website.com).
To fix the problem, remove the quotations or any other irregular symbols and resend your email.
Issue Error Messages:
Task ‘Mailer – Sending’ reported error (0x800CCC0F) : ‘The connection to the server was interrupted. If this problem continues, contact your server administrator or ISP. The server responded: 501 Too many syntax or protocol errors’
Common Causes for the error include:
- A misspelled email address in the To: field (most common)
- Improper Characters in the To: field Eg: < > [ ] etc.
- Leaving a space before or after the email address
- Manually typing the wrong SMTP commands into a terminal window
- A mail filtering or mail scanning plugin which is integrated into your mail client Eg: An Anti-Virus or Firewall
- An old / incorrect message lying in your Outlook Outbox folder.
Solution:
When sending emails using outlook you might receive the error above. It seems that when you copy & paste the email addresses into the To field, they include quotations around them that the server did not know how to handle (i.e. ‘name@website.com’ instead of just name@website.com).
Remove the quotations & then try sending emails.
Today one of my customers reported an error while sending emails from Outlook / Outlook Express, after investigating Exim logs I found this:
SMTP connection from [90.29.110.197]:63138 (TCP/IP connection count = 3) SMTP call from (PEMVAR54) [90.29.110.197]:63138 dropped: too many syntax or protocol errors (last command was "RCPT TO: <'[email protected]'>")
This error can be also related with an error code: (0x800CCC0F): ‘The connection to the server was interrupted. If this problem continues, contact your server administrator or ISP. The server responded: 501 Too many syntax or protocol errors’
How can I fix it?
When you are sending your emails, ensure you are copying and pasting the email address ok, ensure it doesn’t have any special characters like quotations around the email address, as this is interpreted as a strange character and your Email server doesn’t know how to handle it.
In clear words, type the email again, ensure there are no weird symbols or characters and that’s all, it should be working.
501 Too many syntax or protocol errors – Outlook / Outlook Express
Issue Error Messages:
SMTP call from (workstation) [xx.xx.xx.xx] dropped: too many syntax or protocol errors (last command was “RCPT TO: Task ‘Mailer – Sending’ reported error (0x800CCC0F) : ‘The connection to the server was interrupted. If this problem continues, contact your server administrator or ISP. The server responded: 501 Too many syntax or protocol errors’ Solution:
When sending emails using outlook you might receive the error above. It seems that when you copy & paste the email addresses into the To field, they include quotations around them that the server did not know how to handle (i.e. ‘[email protected]’ instead of just [email protected]). Remove the quotations & then try sending emails.
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My clients server access keeps getting blocked by CSF.
The Exim log produces:
no host name found for IP address X.X.X.X
Exim error SMTP call from [X.X.X.X]:50135 dropped: too many syntax or protocol error.
Am I correct in assuming that this can only be solved by the ISP or connectivity provider?
HBruijn
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asked Oct 27, 2015 at 8:16
The lack of reverse DNS record is something that should be addressed/facilitated by the owner of the ip-address, typically indeed the ISP or connectivity provider.
The is not the cause of the second error:
too many syntax or protocol error
That is caused a crappy SMTP client that doesn’t adhere to the standards (which is typically a good indication of a Spambot).
You can tune that behaviour with the smtp_max_synprot_errors setting.
answered Oct 27, 2015 at 10:14
HBruijnHBruijn
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