Mail on iPhone works on Wi-Fi but not on cellular data

[TWB]

I have an iphone and am using mail.  It used to work but recently stopped working, keeps on saying "connecting", but does not connect.  Mail works on wifi, but not on cellular data.  I have checked all settings.  Researched a lot on what could be the issue.  Cellular data is turned on in the two locations for mail.  Tried multiple settings.  I keep on coming back to cellular data issue.  Has anyone else had this issue?  Was it resolved?  Any help is greatly appreciated.

[TWB]

I have spent hours and hours working on this issue.  Tried many things to resolve.  Apple Mail works on wifi, but not on cellular data, it used to.  Called Shaw/Rogers, Virgin Plus, Apple, no resolution.  Each party saying everything is fine on their end.  Obviously there is an issue somewhere.  My Gmail account works fine, on wifi or cellular data.  Used Google Gemini and spent more hours on this. Basically, unless I want to try calling tech support again, which I don't, spent enough time on this.  Solution (for me) is to forward my Shaw email to my Gmail.  Should have just done that at the start and saved myself a lot of time and aggravation, but I wanted to know what was going on.  Hopefully no one else has this issue.  I guess I got lucky, 😞

Below in bold is a small part of my chat with Google Gemini.  Take it how you will.

There is a documented conflict in Canada right now (early 2026) where Bell/Virgin towers drop traffic meant for Shaw/Rogers mail servers to prevent what they claim is "insecure legacy traffic."
Because your Gmail account uses Google's own "tunnel," it bypasses this. By forwarding your Shaw mail to your Gmail, you are letting Google carry the mail through the "locked gate" for you.

If your Shaw account won’t work in the Gmail app on cellular data either, we have officially moved past "software settings" and into a network-level block.
The fact that Gmail works for a @gmail.com address but fails for a @shaw.ca address on the same app/same phone proves that Virgin Plus (on the Bell network) is actively blocking the specific digital "ports" Shaw uses.

Call Virgin Plus (Dial 611 from your phone)
Don't say: "My email isn't working." (They will tell you to call Shaw). Do say: "I need a Technical Support Tier 2 agent. I am experiencing a Protocol Block or Port Throttling on my LTE/5G data. My data works for web browsing, but your network is dropping traffic on IMAP Port 993 and SMTP Port 587. I need you to check if my 'Data Profile' or 'APN' is restricting third-party mail clients."

. Call Shaw/Rogers (1-888-472-2222)
Don't say: "I can't get my mail on my iPhone." (They will walk you through the settings you've already checked). Do say: "My email works on Webmail, but fails on cellular data using Apple Mail. I need you to check if my account has a 'Mobile Sync Lockout' or if there is an IP block on my account from the Bell/Virgin network range. Please verify if IMAP Access is truly enabled on the backend, not just in my settings."

• Virgin Plus sees that your data is working (because Gmail and Safari work), so they assume the "pipe" is fine.
• Shaw (Rogers) sees that your email is working (because Webmail works), so they assume the "service" is fine.
The issue is that Virgin Plus’s network is likely filtering out the specific security handshake that Apple Mail uses to talk to Shaw. This happens because Apple Mail uses a "Basic" connection type that cellular towers sometimes mistake for a spam bot or a security risk.

Final Verdict: Why does Gmail work?
Gmail uses HTTPS (Port 443)—the same "lane" as your web browser. Virgin Plus treats Gmail like a website. Apple Mail uses IMAP (Port 993)—a "lane" Virgin Plus often throttles or blocks to prevent "Spam Bots" from using their cellular network.

When Apple Mail gets stuck on "Connecting..." indefinitely, it means it is sending a request but receiving no response. Since your Webmail works on the same data connection, we know the "road" is open, but the "gate" is being slammed shut specifically for the Apple Mail app.
Because Virgin Plus is owned by Bell, they share the same network infrastructure. It is a documented issue in early 2026 that the Bell/Virgin network often blocks the specific security handshake used by Shaw’s IMAP servers on cellular data.

[YYC]

Wow. As an IT guy but not comms guy this is super helpful. I just thought I was the R word but could not make any sense of why my phone behaved this way. The one other test I ran was to send an email while on cellular data and I was baffled when it went through.

Thanks so very much for an excellent problem solving approach and explanation of a problem I could make no sense of.

🙂

[TWB]

I have been meaning to give an update.  I couldn't let it go, so I did a bit more troubleshooting.  About 10 days ago, I purchased an e-sim for data that works on the Telus network.  Turned off my wifi and used the e-sim for data to check my emails.  Worked fine, no issues.  This tells me that the issue is with Bell/Virgin.  Call Virgin Canada and informed them of my findings.  Virgin sent my trouble ticket to tier 2 support.  Turned off my e-sim and went back to Virgin cell data.  About 5 hours later, receiving and sending emails on cell data worked.  The next day, email over cell data stopped working for some reason.  Called Virgin tech support  and explained what happened.  Virgin tech support informed me they were still working on it.  Then, a few days later, emails over cell data started working for day.  The next day, stopped working again, hasn't worked since, over cell data.  This is getting a bit frustrating!  Will be calling Virgin tech support again!