Intermittent Blocking of IMAP Ports for Email Server

[tony22]

I'm experiencing intermittent issues connecting to my hosted email server while on Virgin Media’s network. This issue affects my ability to access email on both my Mac and iPhone when connected to Virgin. The problem seems specific to IMAP ports (993 for secure IMAP and 143 for standard IMAP) and does not occur when using a VPN or mobile tethering.

Sometimes, I can connect without issues, but at other times I receive connection timeouts. When I tether to my phone or connect via VPN, everything works fine, suggesting the issue is specific to Virgin Media’s network.

When the problem is occurring, I can still connect to port 80 but 993 and 143 timeout. DNS resolution consistently resolves.

Given the behavior, it seems like there may be some filtering or throttling on Virgin Media’s end affecting email-related ports. Has anyone else encountered this issue? Is there any way to relax filtering on these ports or whitelist specific IPs to ensure consistent connectivity?

[Daniel_Et]

Hi @tony22, thank you for your post.

We're sorry to hear about the issues you've been having 😔

I can see you've spoken to the team since you posted. Are you any further forward with this?

Please pop back to us at your earliest convenience.

Regards,
Daniel

[tony22]

Hi Daniel,

Thanks for your reply. It has improved somewhat in terms of frequency but is still intermittently not allowing a connection to the email server.

Thanks,

Tony

[tony22]

Happening again this morning. Can't retrieve email.

[Adduxi]

What Hub are you using?  Have you switched off Web and Child Safe on your MVM account?  If you had a spare router you could try modem mode and your own router to rule out and DNS issues

[tony22]

Thanks for your reply. I'm using Hub4. Yep, switched off all safety features. I could try the router, as I do have another. Although, DNS does resolve and I can get to port 80, so not sure it's that.