I have to admit I didn’t know that until yesterday, when one of my emails got rejected.  I’m sure it is buried somewhere in the FIOS services agreement, amongst all the other small print nobody ever reads.  But it’s true – Verizon scans every outbound email, as outlined here.

While I applaud Verizon’s commitment to fight Spam originating from its network, the implementation seems somewhat flawed and overreaching.  Verizon was one of the early ISP’s to block outbound traffic on port 25, forcing all outgoing email to be relayed through its own mail servers.  That is a sensible approach to blocking infected zombies from spewing Spam, since only authenticated clients can send messages, and the number of messages can be monitored and governed by subscriber IP.  In fact, Verizon also has specific mail recipient limits in its email use policy.

Are there any restrictions on the number of E-mails I send?
Yes. The following restricions apply to the number of e-mails you send:

• You may not include more than 100 recipients in a single email.
• Messages will not be sent to any recipients in excess of 100.
• You may not exceed 500 recipients in 1 hour.
• Exceeding 500 recipients in 1 hour will result in the suspension of your ability to send email for 24 hours.
• This does not affect your ability to receive email.

None of this had ever impacted my typical sending habits until yesterday.  A single message to my mortgage broker containing some innocuous follow-up and an encrypted pdf attachment was suddenly rejected by a Spam filter.  I first assumed that my message was bounced by the recipient’s filter, but on second glance I realized that my own ISP (Verizon) was blocking my email.

Your message did not reach some or all of the intended recipients.
Subject:    RE: request
Sent:    4/14/2009 5:44 PM
The following recipient(s) cannot be reached:
[removed] on 4/14/2009 5:45 PM
You do not have permission to send to this recipient.  For assistance, contact your system administrator.
<mail.[removed].com #5.7.1 smtp;550 5.7.1 The message you attempted to send was determined to be spam. Please visit http://www.verizon.net/spamfaq for more information.>

Verizon just decided unilaterally to block my message. That’s it! No further explanation, no self-service interface, only this ridiculous-sounding suggestion for a remedy:

If you feel we identified your email in error, you may forward the suspected email message as an attachment to spamdetector.update@verizon.net . The message will be examined by third party anti-spam experts. If the message is found to be legitimate, Verizon is notified to adjust or modify the spam filter which caught your message. You will not receive any notification following the review process.

Sure, let me hurry and send my personal emails to some unidentified 3rd party for inspection.

I decided to pass on that and instead use an alternate SMTP service provided by NO-IP.  For only ~$20/year I can freely send messages to up to 150 recipients a day. Good enough for me.