Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Thunderbird Desktop 157.0, released September 30, 2026, lists fixes for a status bar that could keep running and drive CPU usage to 100% after activity ended, two OpenPGP key-handling problems, and three IMAP failures. Mozilla’s release notes identify the symptoms, but do not quantify how many users were affected or explain the underlying causes. Version 157.0.1 followed on October 1 with a separate EWS/Graph crash fix.
Thunderbird 157.0 release notes · Thunderbird 157.0.1 release notes
As an Amazon Associate I earn from qualifying purchases.
What Thunderbird 157.0 fixes
Mozilla’s 157.0 “What’s Fixed” list names these CPU, OpenPGP and IMAP defects. The wording describes possible symptoms, not a claim that every Thunderbird user experienced them.
| Area | Issue Mozilla says was fixed |
|---|---|
| CPU | The status bar could remain active after activity ended and cause 100% CPU usage. |
| OpenPGP | Key discovery could fail to find replacement keys after a key was revoked. |
| OpenPGP | Valid RSA OpenPGP keys could be rejected, preventing encryption. |
| IMAP | Messages could silently fail to save to the Sent folder. |
| IMAP | Account setup could hang while waiting for the IMAP server greeting. |
| IMAP | Messages could disappear while a move within the same account was pending. |
These descriptions come from Mozilla’s Thunderbird 157.0 release notes. They do not name affected operating systems or IMAP server vendors, provide reproduction steps, or report independent testing.
#1 Best Overall
What the CPU fix means—and what it does not
The 100% figure is the symptom Mozilla associates with a status bar that could remain active after work had finished. It is not a measurement of typical Thunderbird CPU use, a prevalence estimate, or evidence that the application generally consumes all available processing power.
The release notes do not give a platform-specific explanation, code-level cause, or workaround for this 157.0 defect. Mozilla Bugzilla’s Bug 1973621 records a separate historical status-bar CPU report, including a reporter’s observation about disabling the status bar and a maintainer’s discussion of a progress-bar workaround. That background does not establish the cause of the 157.0 issue or make disabling the status bar its official fix.
Two separate OpenPGP key problems
Replacement keys after revocation
One fix concerns discovery failing to find replacement keys after a key was revoked. Mozilla’s notes do not specify the discovery mechanism, key services involved, or which configurations were affected.
Valid RSA keys rejected
A separate fix addresses valid RSA OpenPGP keys being rejected in a way that prevented encryption. The release notes do not provide algorithm or compatibility details, so they do not support a broader claim about RSA keys or OpenPGP encryption generally.
Version 157.0 also changed how remote content is handled in OpenPGP messages encrypted with integrity protection. Mozilla lists that as a behavior change, distinct from the two key-related fixes; it should not be mistaken for another fix to key discovery or RSA-key acceptance.
Which IMAP problems are covered
Sent messages not saved
The notes list a defect in which messages could silently fail to save to the Sent folder. They do not say which account settings or servers triggered it.
Rank #4
Account setup waiting for the server greeting
Thunderbird could hang while waiting for an IMAP server greeting during account setup. Mozilla does not provide a server-by-server compatibility list or specify how long users might wait.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Messages disappearing during a same-account move
A pending move of a message within the same account could make the message disappear. The notes do not say that all moves, accounts, or IMAP providers were affected.
Best Value
157.0 versus 157.0.1
Thunderbird 157.0 was released September 30, 2026. The follow-up, 157.0.1, was released October 1 and lists a separate crash fix involving EWS/Graph messages with relative URL fragments. It is not listed as an additional CPU, OpenPGP, or IMAP fix.
For the exact changes, consult Mozilla’s 157.0 notes and 157.0.1 notes. The notes establish the stated defects and release dates; they do not disclose implementation details or independent verification.
Other changes in 157.0
The release notes include changes beyond the fixes covered above. They mention optional manual ports for IMAP/POP configuration and removal of bundled RNP command-line utilities. Those are release changes, not the IMAP defect fixes. The notes also list a Quick Filter UI issue, sender display, OAuth authentication, CardDAV, MIME display, message filters and calendar issues among the other items addressed.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsQuick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
